RESEARCH STATION FOR FRUIT GROWING BRUGSTRAAT 51, 4475 AN WILHELMINADORP, THE NETHERLANDS

RESEARCH STATION FOR FRUIT GROWING BRUGSTRAAT 51, 4475 AN WILHELMINADORP, THE NETHERLANDS Informtion contined in this report my not be reproduced in totl or in prt without permisse-n Price Dfl. 12.50

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C O N T E N T S pge REMARKS ON THE BRANDS OF PESTICIDES AND HERBICIDES 5 DONOR MEMBERS 5 BOARD 6 STAFF 7 DEPARTMENT FOR POMOLOGY AND ECONOMICS Top fruit Rootstocks nd interstems for pome nd stone fruits (rootstocks - 10 interstems) Regultion of fruit set,fruit growth,fruit drop,nd vegettive 20 growth (thinning - colour improvement of Jongold by the use of slts - growth inhibition - pollintion) Unusul fruit crops (wlnut - pech - pricot - lmond - medlr - 25 quinces - hzelnut - kiwi or Chinese gooseberry - Siberin gooseberry - blck ppleberry) Reserch in the fruit-tree nursery (continer trees - receipt of 28 continer-grown trees in the orchrd - plnting distnces - trunk clening - heding bck fter one yer - fertigtion - defolition) Plnting systems (plnting system tril with slender nd North-Hollnd 34 spindle - interntionl plnting-system tril - plnting-system tril with per - plnting-system tril with pple: rrngement nd tree height) Pruning (trining of young pple trees - trining of the centrl leder 42 of young pple trees - plum pruning) Evlution of top-fruit cultivrs Cultivr testing with pome fruits (pple - per) 45 Cultivr testing with stone fruits (plum) 50 Smll fruit section Culture experiments with strwberries (comprison of first progeny of 50 tissue-culture plnts nd norml plnts - slow-relese fertilizers - trils evluting wter-ttrcting chemicl - tste nd shelf-life of glsshouse strwberries - tste of strwberries in the open)

Cultivr testing of strwberries (first screening - ntionl cultivr 53 trils ) Culture experiments with rspberries nd currnts (rspberry - 54 red currnt) Cultivr testing of rspberries, blckberries, gooseberries nd currnts 56 (rspberry - blckberry - gooseberry - red currnt - white currnt - blck currnt) Economics section Anlysis of differences in production nd profitbility of fruit holdings 62 in different production regions DEPARTMENT OF SOIL FERTILITY AND PHYSIOLOGY Soil fertility Trickle irrigtion 64 Fertigtion (experiments in Wilhelmindorp - experiments inother 64 experimentl orchrds) Prediction of storbility on the bsis of fruit nlysis (improvement 66 of prediction - erly fruit nlysis) Physiology Pre-hrvest physiology of fruits in reltion to fruit qulity (effect 68 of reltive humidity on minerl supply of pple fruits - dily growth rhythm of pple fruits) Growth regultors nd tree behviour (Cytokinins in xylem sp of pple - 69 bscisic cid inbuds of pple - ppliction of growth regultors) CROP PROTECTION DEPARTMENT Testing of crop protection chemicls in fruit growing (pple - 71 rspberry - strwberry) Supervised control of scb nd mildew on pple 72 Biology nd control of secondry or spordic diseses in fruit crops 74 (pple - gooseberry - strwberry - per) Integrted control of per suckers nd other pests of per 75 LIST OF CHEMICALS 77 PUBLICATIONS 78

R E M A R K S ON THE BRANDS OF P E S T I C I D E S AND H E R B I C I D E S The dosges mentioned for pesticides nd herbicides in this report refer to the commercil products.trde nmes of products hve been used for the ske of convenience,but this mkes it unvoidble tht in some cses similr products on the mrket under other trde nmes re not mentioned. No endorsement of nmed products is intended. A list of the commercil products mentioned in this report nd their ctive ingredients is given on pge 77. Some of the experiments described in this report re being crried out with chemicls nd/or concentrtions not yet leglly pproved. DONOR M E M B E R S Those who re interested in the work of thereserch Sttion nd wish to keep in ctive touch with nd support its reserch,re invited to become donor members. Donor members will receive the Annul Report nd other publictions of the Reserch Sttion without chrge. The minimum subscription for donor membership is 35 guilders for privte individuls inthe Netherlnds, 60guilders for institutions in The Netherlnds nd 50 guilders for foreign privte individuls nd foreign institutions, nnully. Pyment by trnsfer to n ccount of the Proefsttion voor de Fruitteelt (post office giro ccount nr 49 50 17, ccount with Amro-bnk Goes nr 47.21.74.878)or by interntionl postl money order in Dutch currency, pyble to the Proefsttion voor de Fruitteelt t Wilhelmindorp, with the indiction "Donor Subscription".

BOARD (31th December 1986) BOARD OF THE FOUNDATION RESEARCH STATION FOR FRUIT GROWING Executive committee J.L. Nijsten, chirmn A.G. Elshof, vice-chirmn W.de Jger, secretry Ir. J.L. Ebbens Mrs.Ir.G.M.J. Loeffen Other members Ing.J. Burger J. Crielrd S. Duvekot Ir.H.A. Gonggrijp J.A.M. Musters P.M. vn Veldhoven J. Zevenbergen vcncy Advisors Ir.J.D. Bijloo Ir. A. Groot E.H.M. Jongerius H. Hgenrs

STAFF (31th December 1986) R E S E A R C H S T A T I O N FOR FRUIT G R O W I N G Director: Ir. R.K. Elem Deputy Director: Dr.Ir.H.J. vn Oosten DEPARTMENT FOR POMOLOGY AND ECONOMICS Dr.Ir.S.J. Wertheim (hed) Top fruit Dr.Ir. S.J. Wertheim (hed nd reserch worker) Mrs. Drs. P.S. Wgenmkers (reserch worker) J.M. de Groene F. Nijsse A.J.P. vn de Wrt Evlution top-fruit cultivrs Ing. P.D. Goddrie (reserch worker,sttioned by the Institute for Reserch on Vrieties of Cultivted Plnts (RIVRO)t Wgeningen) F. Nijsse Smll fruit Ir.J. Dijkstr (reserch worker) A.A. vn Oosten Economics J. Goedegebure (reserch worker,sttioned by the Agriculturl Economic Reserch Institute (LEI)t The Hgue) M.L. Joosse SOIL FERTILITY AND PHYSIOLOGY DEPARTMENT Dr. J. Tromp (hed) Soil Fertility vcncy (hed nd reserch worker) Lbortory J. Oele (hed nd reserch worker crop nlyses) H. Andi Gnjoe Mrs. P.C. Rijk Field nd pot trils Ing. P.J. Bolding

Physiology Dr.J. Tromp (hed nd reserch worker) Lbortory Mrs.J.C. Ov (hed) Mrs. M.Th.Th. de Leeuw-Vereecken Mrs. A.M. Meermn-vn de Repe Field nd pot trils Ch.A.R. Römer CROP PROTECTION DEPARTMENT Dr.Ir. H.J. vn Oosten (hed) Mycology Drs. H.A.Th, vn der Scheer (reserch worker) W. Remijnse H.J. Wondergem (sttioned by the Ntionl Bord of Agriculturl Reserch TNO t The Hgue) Entomology Ir.J. Woets (reserch worker) Mrs. C.H. Kersten ADMINISTRATION J.A.M. Kouwenberg (hed nd ccounts officer) Typing stff Mrs.J.G. Snterse-vn Loo (director's secretry) Mrs. T.L. Buizer-Schuit Mrs. M.S. Korsuize Mrs. A.M.Th, vn de Rijt-Mteijsen Mrs. P.E. vn Vossen-Hopmns Housekeepers Mrs. P.C. de Smidt Mrs. M.M. Stuck Mrs. D.N. Nijsse-Hoogesteger STATISTICAL ANALYSIS AND DATA MANAGEMENT J.P.A. vn Dieren (sttisticin) Mrs.J. de Groene (sttioned by the experimentl orchrd t Horst)

SYSTEMATICS ANALYST W. Beeke LIBRARIAN AND EDITOR Mrs. M.M. Cremers-vn Scherpenzeel TECHNICIAN J. vn Dlen EXPERIMENTAL GARDEN J.L. Brends (mnger nd liison officer top fruit) Top fruit P. Proost (deputy mnger) D.R.M. Acd A.A. Jnse M.C. vn Mris A. de Witte Smll fruit J. de Schipper (deputy mnger) J. vn der Ms N A T I O N A L FRUIT A D V I S O R Y S E R V I C E Ntionl fruit dvisor Ir. R.K. Elem Economics Ir. H.L.Bos Top-fruit extension Ing.C. Kortleve Smll-fruit extension nd regionl reserch Ir.J. Dijkstr Top-fruit regionl reserch Ing. J.H. Bootsm (sttioned t the experimentl orchrd t Krggenburg) A. Scholtens (sttioned t the experimentl orchrd t Geldermlsen)

10 D E P A R T M E N T FOR P O M O L O G Y AND E C O N O M I C S TOP FRUIT ROOTSTOCKS AND INTERSTEMS FOR POME AND STONE "FRUITS S.J. Wertheim Rootstocks Apple M.27 types A tril ws plnted in the spring of 1981 with Golden Delicious clone B on 2 types of M.27, one with thorns in the stoolbed, the other without, to see whether this difference would be expressed in orchrd behviour.the tril ws performed in 7 one-tree plot replictes nd ws terminted t the end of 1986. During the 6 growing sesons,the men trunk circumference incresed by 6.3 cm on the non-thorned nd 6.2 cm on the thorned M.27. This difference isnot significnt. Neither totl kg per tree (30.3 vs 29.2)nor totl kg production per cm finl trunk circumference (3.1 vs 3.0 kg/cm)differed between the two M.27 types nd the sme holds for verge fruit weights (159 vs 155 g), numbers of burr knots on the bove-ground rootstock prts,nd root suckers. Thus, orchrd behviour ws not ffected by the presence or bsence of thorns où the M.27 rootstocks in the stoolbed. M.2 types In the spring of 1981 tril ws plnted with Golden Delicious 'Smoothee' on 2 types of M.2. One (T.161) rooted poorly in the stoolbed, the other (T.751) freely.the im of this tril performed in 6 one-tree plot replictes ws to find out whether differences in rooting cpcity ffects orchrd behviour. The tril ws terminted in 1986. The trunk circumference incresed by 19.4 cm ont.161 s ginst 18.8cm on T.751; but this difference isnot significnt. Similrly, the finl tree volume, mesured in November 1986,did not differ significntly (1.69vs 177 m ), nd the sme holds for the totl yield per cm finl trunk circumference (3.0 nd 3.1 kg)or per m of finl tree volume (41.2 nd 40.3 kg). Fruit sizes did not differ either (147 nd 148 g). The men numbers of burr knots per tree on the bove-ground prt of M.2 were 0.8 (T.161)nd 1.8 (T.751). Root suckering did not differ. Thus, the well-rooting T.751 only hd slightly more burr knots. This nd the better rooting cpcity might be expressions of juvenility. M.26 types In the spring of 1981 tril ws plnted with Golden Delicious clone B on 2 M.26 types,one with nd the other without thorns in the stoolbed. The tril comprised 11 replictes nd 2 trees per plot,nd ws terminted in 1986. Over the 6 growing sesons the increse in trunk circumference ws 14.5 on

11 the non-thomed nd 14.4 on the thorned M.26, non-significnt difference. There were lso no differences in either ccumulted kg per tree for the1982-1986 period (75.9 vs 77.9)or totl production per cm finl trunk circumference (4.1 vs 4.2). Fruit weight verged for ll yers ws 173 g for both types. The number of burr knots incresed slightly up to 1986. In tht yer the thorned M.26 showed 3.5 of these root initils per tree,the non-thorned 1.8. Root suckering did no differ. In short,in the orchrd the two M.26 types differed only in the number of burr knots,the thorned (juvenile) type hving more. M.9 types With Rode Boskoop Schmitz HUbsch nd Lombrts Clville s cultivrs, tril including 6 M.9 types ws plnted in the spring of 1981. The tril ws lid in 6 replictes with 2 trees per plot. The M.9 types included for selections of the Generl Netherlnds Inspection Service for Arboriculturl Produce (NAK-B) (T.337 tot.340) nd Belgin (Nicoli 29), nd Germn M.9 (Burgmer 1). The im ws to seewhether differences between these types visible in the rootstock nursery would be expressed in the orchrd. The tril lsted until theend of 1986, nd the min results, verged for both cultivrs, re summrized in Tble 1. Averging ws permissible becuse interction did not occur between cultivrs nd rootstocks. As Tble 1 shows,the 6 M.9 types did not differ in growthvigour or production cpcity. The sme holds for burr-knot formtion on the bove-ground prts of them.9 (not shown). Tble 1. Results of M.9-type tril with pple. Clville nd Rode Boskoop Vlues re mens for Lombrts M.9 type Trunk circumference (cm) end 1986 Tree, volume (m ) end 1986 Kg /cm* trunk circumference Kg/m 3 * tree volume Burgmer 1 Nicoli 29 T.337 T.338 T.339 T.340 13.6 13.9 14.2 14.1 14.4 14.6 0.82 0.80 0.89 0.79 0.86 1.00 3.3 3.4 3.5 3.5 3.5 3.5 54.7 58.1 55.9 62.3 58.3 58.1 * Accumulted kg/tree 1982-1986 divided by the finl trunk circumference or tree volume. Vlues in the sme column followed by the sme letter do not differ significntly (P = 0.05). In second tril with Golden Delicious clone B plnted in the spring of 1982 2 NAK-B types (T.337 nd T.339) nd 6 selections of M.9 from the Fleuren Nurseries (Brlo, The Netherlnds) were compred. So fr, selection nr.56 hs grown less thn the others, whose growth rte hs been similr.for production, too, differences were negligible, except tht nr.56 yielded slightly less thn T.339. Smll differences in numbers of burr knots per tree were noted; for exmple,t.337 hd 1.2 per tree, T.339 hd 2.6,nd nr.56hd 2.3. The lowest number ws found for selection nr. 4, which hd 1.0.

12 In third tril plnted with Elstr in the spring of 1982, 4M.9 types were included (Tble 2), viz. the NAK-B selection T.337,the Germn Burgmer 3, nd 2 Belgin selections from Nicoli, nos. 8nd 29. At theend of 1986, both Nicoli selections hd thicker trunks (Tble 2). However, differences in tree volume nd production per unit of growth were not significnt. So fr,the Nicoli selections hve slightly more burr knots, possibly s n expression of higher degree of juvenility. Tble 2. Results M.9-type tril with Elstr M.9 type Trunk circumference (cm) end 1986 Kg/cm* trunk circumference Burr knots/ tree T.337 Burgmer 3 Nicoli 29 Nicoli 8 15.8 16.1 b 16.8 bc 17.2 c 1.9 1.9 1.8 1.9 1.2 b 0.8 1.8 b 1.8 b * Kg/tree ccumulted for 1982 till 1986 divided by the finl trunk circumference. Vlues in the sme column followed by the sme letter(s) do not differ significntly (P = 0.05). In fourth tril, severl Europen M.9 types re being compred with Golden Delicious 'Smoothee' (Tble 3). This tril ws plnted in 1984 in 6 replictes with 3 trees per plot. Some results re summrized in Tble 3.So fr, growth vigour hs differed between certin M.9 types. As ws the cse in one of the other trils, Fleuren nr. 56 is one of wekest types. Production cpcity did no differ nd the sme holds for fruit weight nd colour (Elstr) nd burr-knot formtion. Tble 3. Results of M.9-type tril with pple M.9 type Golden Delicious 'Smoothee' Elstr trunk circumf. ( cm) end 1986 Kg/cm* trunk circumf. trunk circumf.(cm) end 1986 kg/cm* trunk circumf. Fleuren nr. T.338 T.337 Lncep Burgmer 1 Fleuren nr. Fleuren nr. Burgmer 2 EMLA Nicoli 29 Cepilnd 56 4 59 10.1 10.5b 10.8 bc 10.9 bc 11.1bed 11.2bed 11.2bed 11.3bed 11.4cd 11.7 de 12.2 e 1.2 1.1 1.1 1.1 1.1 1.2 1.1 1.1 0.9 1.1 1.2 10.9 11.4 11.5-11.4 12.0 12.5 12.3 11.6 11.7 - b b b bed d cd bc bc 1.1 1.1 1.0-1.1 1.1 1.1 1.0 1.0 1.1 - * Accumulted kg/tree for 1984-1986 period divided by the finl trunk circumference. ^ Vlues in the sme column followed by the sme letter(s) do not differ significntly (P = 0.05).

13 So fr,the M.9-type reserch results suggest differences in growth vigour nd inburr-knot formtion. However,growth differences hve not shown the sme pttern in the cultivrs tested (Tble 3). Therefore,the question rises Bwhether the observed growth differences justify ny preference for certin M.9 types. Perhps it is too erly to drwn such definitive conclusions. New rootstocks In the spring of 1982, smll tril ws plnted with Elstr on few Est-Europen rootstocks (see Annul Report 1985: p. 12). At the end of 1986 both the Polish P.22nd P.16 hd grown slightly less thn M.9. This isof interest, becuse growers hve been looking for rootstock tht possesses vigour between tht of M.27 nd M.9. Per unit of growth, P.22ndP.16 equlled M.9 in production cpcity.p.16nd M.9 were equl inburr-knot formtion but P.22 ws better in this respect, hving fewer burr knots. P.22 nd M.9 were equl in root suckering, but P.16 gve more suckers.so fr, P.22 seems to be themost promising of this group. P.l, P.2, P.14, P.18,nd B.490 were so much more vigorous thn M.9 tht they re of no interest for Dutch fruit growing. In second tril strted in 1983 with Golden Delicious 'Smoothee' (see Annul Report 1985: p. 13), some dditionl rootstocks were found to be intermedite between M.27 nd M.9 with respect to growth vigour (Tble 4:B.146 nd Jork 9). Others ly between M.9 nd M.26 (Tble 4: B.469, Ottw 3,nd MAC 9), lthough these differences re not significnt. With respect to growth control, B.146 nd Jork 9 re of interest for Dutch conditions. Fortuntely, their production cpcity hs so fr equlled tht ofm.9 (Tble 4). B.146 hs the disdvntge isof hving more burr knots nd roots suckers. Tble 4. Results of rootstock tril with Smoothee Rootstock (origin) Trunk circumf. (cm) end 1986* Kg/tree 1984-1986 Kg/cm** trunk circumf. Burr knots/ tree end 1986 Root suckering index*** end 1986 M.20 (UK) M.27 (UK) 7.8 8.6 b 14.5 14.8 1.8 1.7 b 0.2 0.8 1.5 1.5 B.146 (USSR) Jork (W. Germny) M.9 (UK) 9.6 be 10.1cd 11.0 d 13.8 17.8 18.2 1.4 b 1.7 b 1.6 b 2.9 1.2 0.2 2.5 2.2 1.2 B.469 (USSR) Ottw (Cnd) MAC 9 (USA) M.26 (UK) 12.3 e 12.8 e 13.1 e 13.6 e 16.1 19.2 16.5 16.9 1.3 b 1.5 b 1.3 b 1.2 b 0.4 0.0 0.8 1.3 2.0 1.8 1.7 1.7 B.118 (USSR) B.490 (USSR) 19.4 f 20.0 f 14.4 15.3 0.8 c 0.8 c 1.5 1.7 1.3 1.2 * Corrected for trunk circumference t the beginning of the tril (1983). ** Accumulted kg/tree 1984-1986 divided by trunk circumference t the end of 1986. *** from 1 = none to 5 = mny root suckers. Vlues in the sme followed by the sme letter(s)do not differ significntly (P = 0.05).

14 A third tril strted in 1983 with Jmes Grieve nd Golden Delicious 'Smoothee'on vrious Est-Europen rootstocks (see Annul Report 1985: p. 13) indicted tht t the end of 1986,P.16 nd P.22lso ly between M.27 nd M.9 ingrowth vigour.b.9 grew more thn M.9 but less thn M.26,ndP.l ws more vigorous thn M.26.P.l lso hd mny burr knots, P.16 themost root suckers (Tble 5). P.l must be discrded s too vigorous for Dutch conditions. Tble 5. Results of rootstock tril with pple Rootstock (origin) Trunk circumf. (cm) end 1986* Kg/tree 1984-1986 Kg/cm** trunk circumf. Burr knots/ tree end 1986 Root suckering index*** end 1986 Jmes Grieve M.27 (UK) P.16 (Polnd) M.9 (UK) 7.6 9.2 b 10.7 c 10.0 14.8 18.6 1.3 1.6 1.8 b b 0.4 0.1 0.4 2.0 4.4 2.0 B.9 (USSR) M.26 (UK) P.l (Polnd) 11.3 c 13.2 d 13.3 d 16.4 19.7 19.8 1.4 1.5 1.5 b b b 0.8 1.6 1.9 1.4 1.9 2.1 Golden Delicious M.27 (UK) P.22 (Polnd) P.16 (Polnd) M.9 (UK) 'Smoothee' 8.2 8.8 b 9.6 bc 10.5cd 11.9 15.4 20.8 20.3 1.4 1.8 2.2 1.9 bc d c 0.4 0.2 0.1 0.2 1.9 1.9 3.4 2.0 B.9 (USSR) M.26 (UK) P.l (Polnd) 10.9 d 13.3 e 14.0 e 20.4 23.6 21.7 1.8 1.8 1.5 c bc b 1.5 1.8 5.2 1.8 1.7 2.3 * Accumulted kg/tree for 1984-1986 divided by trunk circumference t the end of 1986. ** from 1 = none to 5 = mny root suckers. Vlues in the sme column (of ech cultivr) followed by the sme letter(s)do not differ significntly (P = 0.05). Ntionl trils re being orgnized with some of the newer rootstocks to ssess both growth control nd winter hrdiness. M.20 versus M.27 In the spring of 1981 tril ws plnted for comprison of M.27 with M.20. Rode Boskoop Schmitz Hübsch nd Jongold were the cultivrs.for ech cultivr there were 5 replictes with 3 trees per plot. Plnting distnce ws 3.50 x 1.50 m. The im ws to seewhether M.20 - never relesed by Est Miling Reserch Sttion, Englnd - ws suitble for ddition to the ssortment of dwrfing rootstocks.the tril ws terminted t the end of 1986. Both in the nursery nd in the orchrd trees on M.20 grew less thn those on M.27. Per tree,ccumulted shoot growth over the first 3 yers (including the period the nursery) ws 12.2 m for Rode Boskoop on M.27 s ginst 7.5 m for M.20. For Jongold these figures were 14.0nd 11.2 m, respectively.at the end of 1986, trunks were thicker on M.27 thn on M.20.For Rode Boskoop, trunk circumferences were 14.9 (M.27)nd 11.8cm (M.20)nd for Jongold 13.7 nd 11.7 cm, respectively. Averged for both cultivrs,this difference (14.3

15 to 11.8 cm)is significnt.finl tree volumes, verged for both cultivrs, differed significntly s well: 0.56 (M.27)nd 0.43 m (M.20). Per cm trunk circumference, totl yield on M.27 ws 3.9 kg sginst 4.3 on M.20. This difference,verged for the 2 cultivrs,is significnt. Thus, trees on M.20 were more productive. This ws lso shown by the difference in totl yield per m tree volume: 105 (M.27)nd 126 (M.20), lthough the difference is not significnt. Fruit size ws similr on both rootstocks. Rode Boskoop hd n verge fruit weight of 230 g (M.27)nd 228 g (M.20)nd Jongold 228nd 231 g, respectively. More importnt ws the observtion tht fruit colour on M.20 ws poorer thn tht on M.27. This ws observed in severl of the yers. This unstisfctory colour together with the higher tendency for root suckering, mkes M.20 unsuitble for use inthe Netherlnds. Per Premture utumnl lef colouring in Conference In the spring of 1984,14 trees representing Conference onquince C were plnted,hlf of which hd shown utumn colours premturely in the preceding lte summer in the nursery. The other 7 trees were helthy. In the course of 1984, 1 tree in the former group died,nd by the spring of 1986 3 were ded. All of the norml treeswere then live. In the spring of 1985,16 trees of Conference on Quince Cnd 16 on Quince Adms were plnted, hlf of which hd helthy ppernce nd the other hlf hd chnged colour premturely in the preceding lte summer in the nursery.by the spring of 1986, hlf of the 'discoloured' trees on Quince Adms were ded. The norml Conference on Quince Adms were ll live,s were ll of the trees on Quince C. These findings men tht premture discolourtion of leves in the nursery should become criterion for condemntion, becuse it leds to substntil losses.the cuse of the phenomenon might be per decline nd/or incomptibility. New rootstocks In the spring of 1984 tril ws plnted with Conference nd Doyenné du Comice on some new rootstocks. New quince rootstocks were included, i.e., the French Sydo ( Quince d'angers),ba.29 ( Quince de Provence),nd the English selection from Cucsin Quince, C.132. The South-Africn per rootstock BP.l ws included s well. Stndrds re Quince And C. Production strted in 1986,nd ws nturlly low.so fr,c.132 hs grown less strongly thn Quince C,n interesting feture. This difference my, however, hve been due to differences in virus sttus, Quince C being virus free nd C.132 not virus tested. Sydo nd BP.l grew s much s Quince A,nd BA.29 ws the most vigorous. More ttention will be given to other per rootstocks in n ttempt to find mteril not subject to thewinter-frost dmge to quinces tht hs occurred regulrly in the lst decde, whether in the nurseries or the orchrds,or both. Inthe spring of 1987 the first tril with Conference nd Doyenné du Comice on Quince C nd the Americn rootstocks 0HxF51 nd 333 ws plnted. Other rootstocks re being propgted or ordered. Budding height on Quince A nd Quince C At the end of 1986 we terminted tril plnted in the spring of 1973 with Conference nd Doyenné du Comice on Quince A nd Quince Cbudded t 10, 20or 30cm bove the ground. ForDoyenné du Comice on Quince A, budding height of

16 60 cm ws lso included.the tril ws crried out in 6 replictes per cultivr with 4 trees per plot. Although high budding on quinces is no longer used becuse of the high risk of winter-frost dmge,some results re given becuse the findings my be relevnt for dwrfing per rootstocks tht re hrdy. Tree-volume mesurements mde t the end of 1986 showed tht there ws significnt negtive correltion between tree volume nd budding height. Tble 6 gives some of the results. Quince A gve lrger trees thn Quince C did. Production cpcity incresed with the height of budding (Tble 6). On Quince A there ws even significnt positive liner correltion between budding height nd ccumulted production per m tree volume. OnQuince C these tendencies were less pronounced. Quince Chd higher production per unit tree volume thn Quince A did. Tble 6. Results of the budding-height tril with per on quince rootstocks Rootstock Budding height (cm) Tree end C volume, L986 (ni) D Kg/m 3 * C D Men fruit weight (g)** C D Quince C 10 20 30 1.35 1.22 1.05 b b 1.58 1.29 1.24 b b 129 141 144 96 113 b 103 b 135 137 134 227 234 231 Quince A 10 20 30 60 2.16 1.92 1.65 - P q r 1.72 1.66 1.46 0.92 P P P q 89 p 97pq 106 q - 66 p 76pq 86 q 122 r 165 p 167 p 161 p - 264 p 264 p 252 q 244 q * Accumulted kg per tree between 1976 nd 1985divided by finl tree volume. ** Averge for ll bering yers (1976-1985). C = Conference; D = Doyenné ducomice Vlues in the sme column (given seprtely for ech cultivr-rootstock combintion to tke interction into ccount)followed by the sme letter(s) do not differ significntly (P = 0.05). Becuse fruit weights were not significntly influenced by fruit numbers per m tree volume,no corrections were mde for the fruit numbers. Averged for ll yers, fruit weight on Quince C ws not influenced by budding height. On Quince A this ws only the cse for Conference; fruit weight of Doyenné du Comice decresed with height of budding (Tble 6). Quince C gve smller pers thn Quince A. Some trees were dmged by the unusully low temperture in the winter of 1984/1985.This ws clerly evident when the rootstock brk ws cut in the spring of 1985 (Tble 7). The cultivr brkws not dmged. Lter,towrd the end of tht summer,dmged trees showed lef discolortions vrying from light green through yellowish-green to purplish-green nd purplish-yellow. In the course of 1986,some of the trees even died. In view of the generl interest in winter-frost dmge,the observtions re summrized intble 7. Rootstock-brk discolortion on the bove-ground prts incresed with budding height,nd ws browner in Quince C thn in Quince A. The rootstock suffered more in combintion with Conference thn with Doyenné du Comice. Lef discolortion minly occurred with Conference; Quince A only hd problems when budded very high (^30 cm). The Conference onquince C combintion suffered especilly bdly. Possibly, insufficient comptibility wekens thequince Cso

17 much tht it ismore prone to winter dmge. Whtever the cuse,this currently common combintion is too sensitive to winter frost.alterntives re being sought. Tble 7. Effects of frost dmge during the winter of 1984/1985 on the trees in the budding-height tril with per on Quince Rootstock Bud' height (cm) Brk colour* spring 1985 Lef colour** 16 Octobe r 1985 % severely dmged trees*** 16 October 1985 C D C D C D Quince C 10 20 30 4.2 c 5.2 d 5.7 d 2.6 4.5 4.9 b b 2.5 3.3 b 3.4 b 1.0 1.3 1.6 58 88 92 0 8 21 Quince A 10 20 30 60 2.9 3.5 b 4.1 c - 2.1 3.2 3.5 4.3 P q q r 1.0 p 1.0 p 1.3 p - 1.0 p 1.0 p 1.0 p 1.8 q 0 0 13-0 0 0 21 * Scle: 1 = white to 5 = drk brown ** Scle: 1 = green; 2 = light green; 3 = yellowish-green; 4 yellowish-or greenish-purple; 5 = ded. *** Trees with vlues >3 for lef colour. C = Conference; D = Doyenné du Comice. Vlues in the sme column (given seprtely for ech cultivr-rootstock to tke interction into ccount) followed by the sme letter(s)do not differ significntly (P = 0.05). Plum The trees of the rootstock tril with Opl nd Reine Clude d'oullins on St. Julien A nd Pixy plnted in 1981 cropped gin in 1986. Accumulted for ll cropping yers (1983-1986),the production of Opl on St. Julien A mounted to 41.4kg per tree, but onpixy only to 19.2. For Reine Clude d'oullins these weights were 14.3 nd 16.3 kg.trees on Pixy were smller. For Opl the tree volume onpixy ws 32% smller thn on St. Julien A, for Reine Clude d'oullins 25%. Productivity per m tree volumewith Opl ws gin lower on Pixy thn on St. Julien A, both in kg (3.9 ginst 5.7) nd in fruit number (125 vs 162) ccumulted for ll cropping yers. With Reine Clude d-oullins Pixy did better: 4.0 vs 2.5 kg per m nd 90 ginst 50fruits per m. Fruits on Pixy were definitively smller. With Opl, men fruit weight in 1986 ws 39 g for St. Julien A nd 33 g for Pixy. With Reine Clude d'oullins these weights were 55nd 42 g, respectively. This confirms findings in erlier yers. In second tril plnted in the spring of 1983, St. Julien And Pixy were gin included,but lso the French rootstock P.2038-1A. Cultivrs re Victori nd Czr. Tree-volume mesurements mde t the end of 1986 showed tht P.2038-1A hs growthvigour tht lies inbetween tht of Pixy nd St. Julien A. Importnt is tht fruit size onp.2038-1a ws equl to tht on St. Julien A (Czr)or even greter (Victori) in spite of n equl (Czr)or higher number

of fruits per tree! However, this interesting rootstock, gives root suckers, which is not the cse for Pixy or St. Julien A. In third tril,strted in 1983, St. Julien A is being compred with the French rootstock Mrinne GF8/1 with Opl s cultivr. Unfortuntely, this new rootstock hs so fr beenmore vigorous thn St. Julien A.At the end of 1986 the tree volume ws 6.4 m for St. Julien And 6.8 m for Mrinne GF 8/1. The second disdvntge is tht trees on the new rootstock cropped less. Thus, expecttions re no longer running high. Interstems Apple M.9 interstem on MM.106 rootstock In the spring of 1981 tril ws plnted with Jmes Grieve nd Golden Delicious clone B on MM.106 with 40-cm interstem of M.9. Hlf of the trees were plnted normlly, i.e., with the MM.106/M.9 union t 10cm bove the ground. The other hlf were plnted deeper, with the sme unionjust below the surfce of the soil. Another subtretment ws plnting with nd without stke for support.the im of this tril, plnted in 6 replictes with 3 trees per plot, ws to see whether the trees could stnd without support,but would nevertheless remin smll due to thedwrfing interstem. The tril ws terminted in 1986. Some results, verged for both cultivrs, re given intble 8. Averging ws permissible becuse the behviour of its cultivrs ws similr. Deep plnting promoted nd omission of support inhibited growth. Deep plnting 'hd negtive effect on the production cpcity, nd the presence or bsence of support hd no influence in this respect. Tble 8. Results of tril with M.9 interstem on MM.106 rootstock, verged for Jmes Grieve nd Golden Delicious clone B 3 Tretment Tree volume- Kg/m end 1986 (m) tree volume* Plnting depth Tree stke Norml + 0.83 80.3 0.75 84.7 Deep + 0.97 b 67.2 b 0.88 b 66.2 b Norml 0.79 p 82.5 p Deep 0.92 q 66.7 q + 0.90 r 73.7 r 0.81 s 75.4 r Accumulted kg/tree between 1982nd 1986divided- by the finl tree volume. Vlues in the sme column prt followed by the sme letter(s)do not differ significntly (P = 0.05). Of the 18non-supported trees plnted normlly 5 (Golden Delicious) nd 1 (Jmes Grieve) stood t slnt.for the deep-plnted trees,these figures were 4nd 0, respectively. Thus, Golden Delicious ws more unstedy thn

19 Jmes Grieve.For the former cultivr, support cnnot be omitted; for the ltter,it my be possible on this rootstock-lnterstem combintion but only if trees re plnted t considerble depth, which Increses vigour nd decreses productivity. But this mens tht the combintion is not relly prcticl in windy region (see lso next tril). Vrious dwrfing interstems on MM.106 rootstock To find out whether tree support could be mde redundnt, we plnted tril in the spring of 1980 with Cox's Ornge Pippin on vrious rootstock-interstem combintions (Tble 9). Interstem length ws 30cm in ll cses. Stndrds were MM.106 interstems nd Zoete Agt interstem on M.9. All combintions were plnted with nd without tree stke in 6 replictes with 2 to 3trees per plot t 3.50 x 1.80 m. However,it ws lredy cler t plnting time tht the trees on the strongly dwrfing interstem 3426 could not remin upright without stke,nd ll of these were given stke.in the course of the yers some of the trees on M.27 nd M.9 interstems were given stke too, becuse otherwise theywould hve toppled over.this ws the cse for 5of the 18 trees on M.27 nd for 2of these on M.9 Among the reminder, some of the trees of these combintions did not remin verticl. Thus,s in the preceding tril, moderte vigorous rootstock combined with dwrfing interstem isnot good lterntive for the use of support. Tble 9. Results of the interstem tril on MM.106 with Cox's Ornge Pippin Tretment rootstock interstem Tree end <m > volume L986 Kg/m 3 tree volume* Men fruit _*** weight (g)** +**** M.9 M.9 Zoete Agt MM.106 1.31 1.30 56.6 66.0 134 128 133 129 MM.106 MM.106 MM.106 MM.106 MM.106 3426 M.27 M.9 MM.106 Zoete Agt 0.29 1.30 1.79 2.95 2.92 c b b d d 104.2 b 63.1 52.7 40.5 42.3 116 b 136 134 136 133 124 135 132 132 129 * Kg/tree ccumulted between 1981 nd 1986divided by the finl tree volume end 1986. ** Averge for 1981 through 1986., *** Without, **** with correction for differences in fruit numbers per m tree volume. Vlues in the sme column followed by the sme letter(s)do not differ significntly (P = 0.05). Some interesting results were obtined with the vrious interstems (Tble 9). In Tble 9, only the vlues for the combintion with stke re given.it should be mentioned here tht the trees without stke showed less growth thn the supported trees. The presence of stke hd no effect on fruit size or production cpcity. The interstem 3426 hd n enormous dwrfing effects. Trees on this interstem were excessively wek nd showed excessive root suckering. Production cpcity ws very high nd fruits were therefore too smll. M.27 nd M.9, too,decresed growth vigour nd Zoete Agt hd no effect. None of these interstems ffected production cpcity or fruit weight. Becuse none of the trees on MM.106 performed better thn the common combintion Zoete

20 Agt on M.9, interstem, combintions with MM.106 hve no prcticl vlue for use inthe Netherlnds. REGULATION OF FRUIT SET, FRUIT GROWTH, FRUIT DROP, AND VEGETATIVE GROWTH S.J. Wertheim Thinning Hnd thinning nd fruit colour of Jongold On mture trees of Jongold on M.9 plnted t 3.40 x 1.50 m, thinning tril ws plnted to study the effect of the degree of thinning on fruit colour. Insufficient fruit colour is the min problem for this cultivr.the 8 tretments (Tble 10) were replicted 9 times with 1 tree per plot. Tble 10. Results of thinning tril for Jongold. Hnd thinning stndrd Fruits/ 100 flower clust. Kg/ tree Fruit weight vs; Colour index* Lef (cm ) spurs re shoots Unthinned 2 fruits/cluster 1 fruit/cluster 1 fruit/2 clusters 1 fruit/3 clusters 1 fruit/4 clusters 1 fruit/8 clusters Totlly thinned 67.3 59.9 48.8 25.9 22.1 17.5 10.3 0.0 86.8 79.1 68.6 36.7 29.9 24.9 13.2 0.0 14.9 15.0 13.8 7.9 6.5 5.9 3.1-173 191 b 201 be 216 c 218 240 d 236 d - 2.4 3.1 3.3 3.7 3.6 3.7 3.8 - b be c be c c 21 23 23 22 22 23 22 21 36 38 36 37 35 36 38 37 * Colour evlution on the tree; scle: 1 = ll visible fruits green,to 5 = ll visible fruits well coloured. Vlues in the sme column followed by the sme letter(s)do not differ significntly (P = 0.05). Flowering ws good, with 155 clusters per tree for the 7th growing seson. The number of flowers per cluster ws 5.4.Fruit set ws good, with 445 fruitlets per tree. However, June drop ws rther strong: for the untreted trees the fruit number per tree decresed from 396 to 87 (281 to 67 per 100 flower clusters). The tretments crried out on July 2nd nd 3rd hd strong effect on production, fruit weight, nd fruit colour (Tble 10, Figure 1). Lef counts nd mesurements indicted tht lef sizews not influenced, but the number nd the re of the leves per fruit were of course ffected. Figure 1 shows, both fruit colour nd weight incresed with lef number. In fct, good colour goes hnd in hnd with high fruit weight,nd this ws confirmed by colour grding. Tble 10nd Figure 1 show tht the thinning leding to good overll fruit colour resulted in very low productivity. One fruit per 2 clusters (ctully 25.9 fruits per 100 clusters)only gve 16ton per h.

21 Frui t weight (g) Colourindex on the tree ( ) 170 2-150 30 50 70 90 110 130 150 170 190 210 230 250 leves /fruit Fig. 1. Reltionship between the number of leves per fruit nd the fruit weight nd the fruit colour of Jongold on M.9. Colour improvement of Jongold by the use of slts Becuse there re indictions in the literture (Phytochemistry 1986 25(3): 607-609)tht NCl cn enhnce red colour-formtion in pple-fruit skin. The following tril ws crried out for Jongold trees. Once (mid-september)or twice (mid- nd end of September), solutions of 1.5, 3,or 6g/1NCl or KCl were spryed on four-yer-old Jongold trees on M.9. The 13 tretments (including untreted trees spryed with wter) were pplied in 5 replictes. In October,fruit colour evluted severl times on the tree showed tht differences between the tretments were negligible. Thus, these slts do not offer solution for the Jongold colour problem. Growth Inhibition Growth inhibition inpple by trunk ppliction of growth regultors On seven-yer-old trees of Jongold onm.9 the effect of ppliction of NAA nd CF 125 on the trunkws evluted. Vrious concentrtions (by weight) were incorported into Topsin M pste (n nti-fruit-tree cnker pint), viz. 0, 0.1, 1.0,nd 5.0%. The pure trde formultions were lso included s pint. Applictions were mde during the first week of My, nd 20 cm of the trunk ws pinted ll round from the union. The tril ws set up with 9 replictes nd one tree per plot. It soon ppered tht both pure nd 5.0%CF 125 were highly phytotoxic.

22 Some of the leves becme discoloured nd dropped, others remined but showed distortion.this shows in ny cse tht the growth regultors hd penetrted into the tree through the trunk.none of the other tretments led to visible dmge to the trees. HighNAA concentrtions nd ll CF 125 tretments inhibited growth,s indicted by thedecresed trunk growth. In untreted trees nd trees pinted only with Topsin M pste trunk circumference incresed by 1.5 cm during 1986.For the vrious concentrtions NAA, this increse mounted to 1.6 (0.1%), 1.3 (1.0%), 1.0 (5.0%), nd 1.0 cm (pure NAA). For CF 125 these vlues were,in the sme order, 1.3, 1.2, 0.5, nd 0.3 cm.the lst twoof thesevlues reflect the dmge done by these tretments. This dmge ws lso expressed by nextremely hevy fruit drop. For exmple,the untreted trees gve 98.6 pples s ginst 19.1 (with 5.0%CF 125) or 11.3 (with pure CF 125). The other tretments did not ffect cropping. High CF concentrtions (5.0% nd pure)inhibited fruit growth s well s red-colour development.the other tretments hd no effect. Reserch on the effect of NAA in this respect will be continued. Pollintion Crossings Crossings were mde with pple nd per cultivrs to estblish suitbility s pollintors. Tble 11 summrizes the results.per crossing, 100 flowerswere used, lwys on 5 trees ech with clusters thinned to 4 flowers.hnd pollintion ws performed in the blloon stge,nd pollinted stigms were immeditely covered with vseline. Attention ws directed minly to new cultivrs.jongold x Jmes Grieve ws lso included,becuse this combintion does not lwys meet the growers' needs. As Tble 11 shows, most of the crosses (including Jongold x Jmes Grieve) gve fruit set of mgnitude indicting tht pollen comptibility isnot problem. However,there were some exceptions. Fiest (=Cox's Ornge Pippin x Idred)pollen ws unsuitble for Elstr (= Golden Delicious x Ingrid Mrie). This cnnot esily be explined in terms of reltionships, which certinly holds for the poor results obtined with IVT 72001-96 ((= Cox's Ornge Pippin x Elstr) x Cox's Ornge Pippin). With respect to per,conference pollen ws stisfctory with 2 IVT numbers but filed with 2 others. The ltter cnnot be explined in terms of reltionship either, IVT 6403-23 being Psse Crssne x Doyenné ducomice cross nd IVT 69025-56 Beurré Hrdy x Doyenné du Comice hybrid. The poor set seen in some crosses underlines the importnce of this type of work. Pollen germintion The percentge of germintion ws investigted for some new pple cultivrs. This percentge is of importnce with respect to the pollintion vlue of cultlvr. Pollen grins were llowed togerminte for 24 hours in 15% sucrose solution t room temperture. IVT numbers 71017-2, 71017-120, 72001-96 nd 75118-39, s well s Fiest, Ktj, nd the stndrd Golden Delicious,hd high germintion percentges, showing tht these cultivrs cn be considered to be diploids. IVT number 71017-46, Jupiter, nd the common Dubbele Zoete Agt (n interstock cultivr) hd low germintion percentges,nd must therefore be triploids. Contrdictory results were obtined with IVT 74117-17, Arlet, Rubinette,nd Sint,nd for these cultivrs the studies must be repeted.

23 Tble 11. Results of crossings with pple nd per Mother cultivr x Pollintor Fruits/100 flower clusters Good seeds/ fruit Apple Arlet Elstr Elstr IVT 74114-17 IVT 74114-17 IVT 74114-17 IVT 71017-2 IVT 71017-2 IVT 71017-46 IVT 71017-46 IVT 72001-96 IVT 72001-96 IVT 75118-39 IVT 75118-39 Jongold Jongold Ktj Ktj Ktj Rode Boskoop Sint Alkmene Fiest IVT 71017-2 Alkmene Cox's O.P. Smoothee Cox's O.P. Smoothee Cox's O.P. Smoothee Cox's O.P. Smoothee Cox's O.P. Smoothee Jmes Grieve Ktj Alkmene Jmes Grieve Vist Bell Ktj Cox's O.P. 45 0 10 75 33 64 21 40 40 35 6 14 14 17 38 34 26 42 30 18 38 7.4-7.3 6.4 1.6 7.1 7.0 2.5 4.2 3.7 3.8 4.3 * * 4.7 3.4 7.4 7.4 6.6 1.3 5.4 Per IVT 6403-23 IVT 68013-38 IVT 690215-56 IVT 70025-1 Conference Conference Conference Conference 3 47 2 18 0.7 1.5 0.5 1.4 * Not counted. Rech of pollintor For estblishment of the rech of pollintor, studies were performed with the ornmentl Mlus 'Bsktong' plnted in the middle of severl orchrds. When pollen of this red-leved Mlus cultivr fertilizes norml pple,the offspring hve only red leves. In the spring of 1980one 'Bsktong'tree ws plnted in the middle of 6 orchrds,t the sme time s the pple trees. The trees strted to ber fruit in 1982.In 8 to 10 wind directions, pple trees stnding 2.5, 5, 7.5, 10, 15, 20, 25, 30, 35,nd 40 m from the 'Bsktong' tree were mrked. The fruit of these trees ws smpled nnully. Seeds from these fruits were prepred, stored t low temperture,nd germinted in heted glsshouse. Green en red seedlings were counted by the colour of the cotyledons. The numerous dt suggest tht 'Bsktong'exerted its influence minly within circle with dimeter of 7.5 m, lthough red seeds - cpriciously distributed nd in low numbers - occurred up to 40 r from the 'Bsktong'.Two trils re still in progress. It must be mentioned tht 'Bsktong' pollen gve high fruit nd seed set fter hnd crossings with Cox's Ornge Pippin, Discovery, Jmes Grieve,

24 Krmijn de Sonnville,Lonibrts Clville,nd Odin. These cultivrs occurred in the prcels under study.in the flowering period, too, 'Bsktong'showed sufficient overlp with these cultivrs to ensure fruit nd seed set. Role of self pollintion Strting in 1984, the role of self pollintion in pple nd per ws studied in reltion to cropping of orchrds with low percentges of pollintors. This study concerned to Cox's Ornge Pippin nd Doyenné du Comice. With Cox's Ornge Pippin no fruit set ws obtined in 1984fter one or two successive self pollintions (t one-dy intervls) performed in the blloon stge. In 1986, fruit set did occur (Tble 12). Nodifference ws found between 1, 2 or 3 self pollintions (gin t one-dy intervls strting in the blloon stge)of 100flowers per crossing (see p. 22). Fruit set ws considerbly lower thn fter cross or open pollintion. Seed set lso occurred fter seifing. Tble 12. Results self-pollintion studies in pple nd per Tretment Fruit s/100 before June drop flowers t hrvest Fruit weight (g) Seeds/fruit good def Cox's Ornge Pippin Open pollintion Cross pollintion lx Self pollintion lx Self pollintion 2x Self pollintion 3x 39 44 12 b 3 b 9 b 22 21 3 b 1 b 7 b 115 120 108 110 98 6.3 6.4 5.8 8.0 4.8 0.0 0.5 0.0 0.0 0.0 Doyenné du Comice Open pollintion Cross pollintion lx Self pollintion lx Self pollintion 2x Self pollintion 3x 4 93 b 3 2 13 c 3 73 b 2 1 3 261 233 220 210 246 1.9 1.5 0.3 0.0 0.1 5.8 5.7 8.3 8.0 9.0 Vlues in the sme column (per cultivr)followed by the sme letter(s) do not differ significntly (P = 0.05). With Doyenné du Comice,fruits nd seeds were obtined in 1984 fter selfing. After 1, 2,3,or 4 self pollintions (gin with one-dy intervls, nd 100 flowers per tretment)finl fruit set mounted to 0, 10, 4nd 1%, respectively. Open pollinted flowers gve 5% fruit set, nd bgged flowers without pollintion 0%. In 1985, too, selfing gve fruits. After 1, 2, 3 or 4 selfings, done s before, finl fruit setmounted to 10, 6, 5,nd 5% fruit set. Open pollintion gve 8% set, bgging lone 1%,nd cross pollintion of non-bgged flowers 2% versus 14%for bgged flowers. In 1986, fruits were gin obtined fter self pollintion, lthough fr fewer less thn fter cross pollintion (Tble 12). Before June drop, 3 successive self pollintions gve significntly better results thn 1 or 2, but there were no differences in finl set. Pers from self-pollinted flowers contined less good nd more def seeds thn those from open or cross

25 pollinted mteril. The results indicte tht,t lest in some yers, (repeted) self pollintion my be responsible for bsic cropping level. UNUSUAL FRUIT CROPS S.J. Wertheim nd J. Dijkstr Wlnut (Juglns regi) The cultivrs plnted in 1981 ll bore fruits in 1986. Brodview gve the most fruits. The verge number for the 3 trees present ws 336 nuts. This cultivr ws themost productive in 1985 too. Resonbly good crops were obtined in 1986 from nr. 1247 (183 nuts), nr. 139 (130 nuts), nr.26 (108 nuts), nd Buccneer (100 nuts). Nr. 120on rootstock Juglns regi gve 77 nuts per tree s ginst 57 on Juglns nigr. Frnquette, too, gve slightly more nuts on regi rootstock; 21 versus 7 nuts per tree. The cultivrs Weinsberg 1, Solèze, Come, nd Prisienne gve only few nuts: 31, 16, 12,nd 9 per tree,these cultivrs being slower in coming into bering. The good cropping behviour of Brodview ws confirmed by the older trees plnted in 1974. Averged for 3 trees, production mounted to 14.1 kg per tree s ginst 5.0 kg for Buccneer.Inboth cses verge weight of the fresh nuts ws 15g. Pech (Prunus perslc) In the spring of 1983,10pech nd 5 nectrine cultivrs were plnted t 4.75 x 3 m in 2 replictes for ech cultivr.this limited tril ws set up solely to ssess- the vlue of these cultivrs for the hobbyist, which in turn hs some relevnce for fruit-tree nurseries. Some fruits were picked s erly s 1984. Ves Oogst gve 10.5per tree nd Ruby Gold 7.5. All of the other cultivrs produced only single fruit.in 1985 the trees did not crop,but they did in 1986. Agin Ves Oogst scored highest, with 43.2kg per tree. Becuse of this high cropping level, the fruits were smll (65 g). Good crops were lso obtined with Erliglow (31.4 kg, 46 g), Johnny Brck (30.8 kg, 78 g), Peregrine (29.4 kg,66 g), Suncrest (26.3 kg, 85 g), nd Wssenberger (20.7 kg, 113 g). The yield of ll other cultivrs ws much lower.the smller fruit size in 1986 my hve been due to long dry period which occurred during the growing seson. The trees re not irrigted. Apricot (Prunus rmenic) In 1983 nd 1984,19cultivrs were plnted for evlution.for ech cultivr, 3 replictes of 1tree ech were plnted 4.75 x 3 m. In 1985 only the old Dutch cultivr Tros Ornje gve fruits (1.6kg per tree), nd in 1986 it ws gin one of the few berers (2.9kg per tree). The second old Dutch cultivr Bredse gve 1.5 kg nd ll of the other cultivrs either did not crop t ll or hd only single fruit.

26 Almond (Prunus dulcis) Most of the cultivrs plnted In 1982 were severely dmged by the winter frost of 1984/1985. Both trees of the French cultivrs Al, Ferrduel,nd Ferrlise were killed.one of the Ferrostr trees froze, s did the Germn Schneiders Auslese.The French Ferrgnes ws bdly dmged but ws still live in 1986. Two Germn cultivrs, Durkheimer Riesen nd Auslese Geisenheim, were undmged. The ltter gve the best performnce: it showed moderte growth vigour nd the trees cropped in 1986 wheres the former ws more vigorous nd did not crop in 1986. On this bsis Auslese Geisenheim looks promising for privte grdens. All trees were grubbed t the end of 1986. Medlr (Mespilus germnic) Themedlr trees plnted in the spring of 1982 cropped gin in 1986. Ech rootstock-cultivr combintion is represented by 3 trees. Bredse Reuzenmispel on hwthorn gve the best yield: 494 fruits per tree (13.5 kg). The selection Westerveld from the NAK-B (Generl Netherlnds Inspection Service for Arboriculturl Produce)on Quince C rootstock ws second with 381 fruits (10.2 kg), followed by Royl on hwthorn with 340 fruits (9.4 kg)nd onquince C with 328 fruits (10.0 kg). For Nottinghm nd Mcrocrp,both on hwthorn, these figures were 192 (4.5 kg)nd 82 (4.2 kg), respectively. Sultn on Quince C cme lst with yield of 69 fruits (2.7 kg). We were surprised to find tht Sultn ws not comptible with hwthorn rootstock. For the hobbyist, Westerveld nd Nottinghm re good medlr cultivrs, becuse the fruit tsted better (in 1985) thn the others. Quinces (Cydoni oblong) In spite of the dmge cused by the low tempertures of the winter of 1984/1985 (see Annul Report 1985: p. 25) most of the quince cultivrs (plnted in 1980)cropped well. Averged for the 3 trees, Re's Mmmoth scored best with 21.1 kg per tree (fruit weight 222 g), Vrnj (on Quince A rootstock) with 20.6 kg (156 g)tking second plce. On Quince C, Vrnj production ws much lower (6.6 kg, 155 g), possibly becuse the ltter rootstock hd suffered more frost dmge. The winter-hrdy Lescovck gve 18.7 kg per tree (126 g), followed closely by Shms with 18.0 kg (164 g). The smll-fruited Ludovic cme next with 14.6 kg (86 g). This cultivr unquestionlly hs ornmentl vlue, becuse of its grceful slightly drooping hbit nd hndsome leves. Isfhm yielded 14.1 kg (164 g)nd Bourgeult 12.0 kg (115 g). The other cultivrs - Chmpignon, Portugl,nd Serbin - were much less productive. The quinces will be grubbed in 1987 becuse spce isneeded for extension of the sttion's buildings.new trees re being grown nd will be plnted in 1988,becuse the processing industry hs shown some interest in the fruits. Hzelnut (Corylus spp.) The tril plnted in the spring of 1981 with the cultivrs mentioned in Tble 13 (3 replictes, 2 trees per plot) yielded gin in 1986. The cultivr Gunslebert hs been themost productive so fr (Tble 13).

27 Tble 13. Results of hzelnut tril plnted in 1981 (plnting distnce 4.5 x 2 m) Cultivr Ton/h* 1986 1983-1986 % nuts free from husk 100 kernel weight (g) 4/11 5/12 % kernel 4/11 % dry mtter 8/12 Northmptonshire Impértrice Eugénie Merveille de Bollwiller Gunslebert Ségorbe Cosford Longue d'espgne Louis Berger 2.6 3.4 1.9 4.5 1.0 2.8 2.9 1.2 5.6 7.0 4.6 11.2 3.8 5.2 6.8 3.0 50 44 58 80 91 73 12 58 93 79 124 133 119 145 88 177 83 71 119 119 112 117 85 155 51 44 38 42 42 59 34 51 90 82 82 82 88 78 77 66 * Fresh nuts. Kernel weight nd weight-percentge kernel vried.the ltter ws very low forlongue d'espgne nd Merveille de Bolwiller,but high for Cosford. Percentge kernel sometimes differed considerbly between 1986 nd 1985 (Impértrice Eugénie dropped from 58 to 44, Gunslebert from 51 to 42nd Longue d'espgne from 53 to 34). However, this ws not the cse for other cultivrs. As Tble 13 shows, with dvncing timenuts lost weight due to drying out. Vribility ws lso found in the percentge of nuts tht dropped without the husk. Here, too,the percentges found in 1986 in some cultivrs differed from those of 1985. Higher pecentges in 1986 occurred for Merveille de Bollwiller nd Northmptonshire, lower ones for Gunslebert, Cosford, nd Louis Berger. In other cultivrs the percentges were equl. Percentge dry mtter ws low for Cosford, Longue d'espgne,nd Louis Berger.For processing,high vlues re wnted. Another importnt feture is detchment of the pellicle surrounding the kernel during rosting. Pellicles detched poorly from kernels of Impértrice Eugénie, Longue d'espgne, Louis Berger nd somewht better for Cosford nd Northmptonshire. Gunslebert ws resonbly good in this respect,nd Merveille de Bollwiller nd especilly Ségorbe were good. Kernel tste fter rosting ws poor for Louis Berger nd moderte for Longue d'espgne. The others were moderte to very good. When ll fetures re considered, Merveille de Bollwiller nd Gunslebert cme out fvourbly. A clerly negtive rting ws given to Impértrice Eugénie, Longue d'espgne,nd Louis Berger. The other two cultivrs hd both good nd bd feturies mking them questionble. In the tril plnted in 1982Lng Tidlig Zeiler hs been themost productive so fr (4.41 ton/h ccumulted for 1985nd 1986). Results will be given in future report. Kiwi or Chinese gooseberry (Actinidi chinensis) Agin severe winter frost cused extensive dmge. Yields were therefore low gin, with 1.7 kg per plnt for Hywrd nd 2.4 kg per plnt for Monty. Menwhile, enough strong young shoots hd grown just bove soil level,so tht in time new hedgerow cn be formed.