Asparagus. Tuesday morning 9:00 am. Moderator: Gene Kokx Jr., Michigan Vegetable Council Board of Directors. 9:00 a.m. Asparagus Virus Survey

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1 Asprgus Tuesdy morning 9: m Modertor: Gene Kokx Jr., Michign Vegetble Council Bord of Directors 9:.m. Asprgus Virus Survey Norm Myers, Ocen Co. MSU Extension 9:15.m. Asprgus Disese Updte Mry Husbeck, Plnt Pthology Dept., MSU 9:45.m. Asprgus Irrigtion: Is It Relly Needed? Dn Drost, Plnts, Soils & Biometeorology Dept., Uth Stte Univ. 1:45.m. Michign Asprgus Advisory Bord Updte John Bkker, Michign Asprgus Advisory Bord

2 Asprgus Disese Updte Dr. Mry K. Husbeck ( ), Dr. Ctrin Sude, nd Jmes Counts, Jr. Michign Stte University, Deprtment of Plnt Pthology Effect of irrigtion nd drip-pplied chemicl nd biologicl tretments on Fusrium crown nd root rot nd Phytophthor crown nd sper rot of sprgus. This study ws conducted on coopertor s frm in Ocen County, MI, in fllow field tht hd been plnted to n sprgus seedbed in 22. Asprgus Jersey Gint crowns were plnted on 13 My 23 t spcing of 7.5 in. with row spcing of 5 ft. Tretment blocks consisted of five rows. Two rows were irrigted every 7 dys, two rows were irrigted every 3 dys, nd one row served s n untreted control with 9-ft. buffer between tretment blocks. Five tretments were replicted 4 times in completely rndomized block design with the 7- nd 3-dy irrigtion intervls lso being rndomized. Inoculum ws prepred using sterile sprgus broth tht ws inoculted with nonpthogenic Fusrium strins F-21 nd D-1, nd incubted for one week. Crown tretments of Topsin 7WSB (.5 lb/a), Scholr 5WP (8 oz/1 gl), or nonpthogenic Fusrium broth (2.6 gl/1 row ft) were pplied s drench t plnting nd then repplied every 3 dys s n irrigtion injection. Mefenoxm (4 pt/a) ws pplied to the outside rows every 21 dys in 24 nd 25. A stnd count ws tken on 2 September 23, 3 August 24 nd 24 August 25. Plnts with shepherd s crook nd Phytophthor symptoms were counted on 14 September 24 nd 24 August 25. The plot ws estblished in 23 under dry conditions, which fvored Fusrium development. In 24, Phytophthor megsperm symptoms, including wter-soking nd shriveling of spers, were noticed during hrvest, possibly enhnced by hevy rins during My. Wether conditions were dry nd cool during Jul nd Aug 24. In 25, hot dry conditions were norml for the growing seson. In 25, rows tht were treted with mefenoxm hd greter set of new growth nd more totl growth thn rows tht did not receive mefenoxm. The tretments of Topsin 7WSB nd irrigtion produced more new growth thn nonpthogenic Fusrium or the untreted (Tbles 1,2; Fig. 1). Tble 1. Averge totl fern when sprgus ws treted with mefenoxm or with drip tretments. Tretment nd rte Totl fern Drip tretment mendment Untreted * No mefenoxm Mefenoxm 4 pt/a b Drip pplied tretments Untreted b Irrigted Nonpthogenic Fusrium 2.6 gl/1 row ft b Topsin 7WSB.5 lb/a b Scholr 5WP 8 oz/1 gl b * Tretments with letter in common or with no letter re not significntly different (P>.5, Tukey- Krmer).

3 Count (per 2 ft of row) A sprgus totl fern count for drip tretment mendments, 25 Count (per 2 ft of row) A sprgus new fern count for drip tretment mendments, 25 b Untreted No mefenoxm Mefenoxm Fig. 1. Totl fern count (left) nd new fern count (right) for sprgus treted with drip mendments in 25. Tble 2. Averge new shoot growth when sprgus ws treted with mefenoxm. Tretments New fern Untreted * 6.6 No mefenoxm Mefenoxm 4 pt/a b * Tretments with letter in common or with no letter re not significntly different (P>.5, Tukey- Krmer). Pthogenicity of Phytophthor sp. on sprgus cultivrs. Two experiments were conducted in growth chmber to evlute the response of 19 sprgus cultivrs to Phytophthor sp. isolted from sprgus in 24. Results from both trils show tht cultivrs Mry Wshington, Thelim, Dulce Verde nd Jersey Gint re especilly susceptible to Phytophthor sp. with disese severity rtings between 4.5 nd 5.3. Grolim nd UC 157 showed resistnce or tolernce with disese severity between 1.5 nd 2.2 (Tble 3). This screening ws useful in differentiting sprgus cultivrs nd these results will fcilitte further screening both in greenhouse nd field. Tble 3: Pthogenicity of Phytophthor sp. isolted from sprgus on severl sprgus cultivrs. Cultivr Disese severity y Cultivr Disese severity Grolim 1.6 z Jersey Supreme 3.3 bc UC Jersey Gem 3.3 bc Tiessen 2.5 b Millenium 3.4 bc Gignlim 2.6 bc Apollo 3.6 bc Grnde 2.8 bc Greenwich 3.8 bc Jersey King 2.8 bc Mry Wshington 4.5 bc Atls 2.8 bc Thelim 4.6 bc Jersey Gint 3. bc Dulce Verde 4.9 bc Jersey Knight 3. bc Jersey Generl 5.3 c y Disese severity rting is 1 to 6 where 1= no symptoms nd 6= plnt deth. z Columns mens with letter in common re not significntly different, SNK (p=.5) Untreted No mefenoxm Mefenoxm

4 Host rnge trils in the greenhouse. Phytophthor sp. isolted from sprgus in 24 is member of the Phytophthor megsperm group tht hs severl hosts. Some species of this group hve been renmed bsed on their specificity to certin crops. To evlute the specificity of the Phytophthor sp. isolted from sprgus, greenhouse trils were conducted in Mrch nd My 25. Plnts of sprgus (Jersey Gint nd Mry Wshington), soyben, lflf nd red clover were chllenged with Phytophthor isoltes from both sprgus nd soyben. Disese severity (1 to 4, 1 = no disese symptoms, 4= plnt deth) ws evluted weekly for 4 weeks. Results indicte the specificity of the isolte from soyben tht cused disese nd deth of ll soyben plnts, but did not cuse significnt disese on sprgus, lflf, nd red clover (Fig. 2). On the other hnd, the Phytophthor isolte from sprgus induced high levels of disese nd/or deth on both sprgus cultivrs but did not significntly ffect soyben, lflf nd red clover. Tril 1 Soyben isolte Asprgus isolte Disese severity (1=-25% infection to 4=>75% infection-ded plnt) b b c c b 1 Soyben Jersey Gint Mry Wshington Alflf Red Clover Fig. 2. Greenhouse host rnge screening for Phytophthor isoltes from sprgus nd soyben.

5 Improving Asprgus Growth through Better Wter Mngement Dr. Dn Drost, Uth Stte University 482 Old Min Hill Logn, UT The sprgus growth occurs when tempertures re wrm enough to initite sper growth in the spring. In temperte production regions (Cnd, Michign, Wshington), environmentl fctors (temperture nd rinfll) tht influence sper nd fern growth (crbohydrte (CHO) storge, bud initition nd growth, root/crown expnsion) will ffect the level of productivity in the next yer. Becuse these re connected but re lso seprted in time, it is often hrd to stte which environmentl condition or crop mngement prctice hs the gretest effect on future growth nd yield. The scope of this presenttion will focus your ttention on how irrigtion mounts nd the method of wter ppliction cn influence the level of production. Plnt Growth Dynmics An sprgus plnt is composed of ferns of different ges (buds, spers, young, mture nd old fern), n underground stem (crown) which supports the fern nd the flesh nd fibrous roots growing off of the crown. During the first few yers fter plnting, growers need to blnce fern nd crown growth (Dufult, 83). After plnting the crown, stored food reserves re used to generte the fern tht mnufctures CHO needed for dditionl fern development nd CHO storge nd root growth (Drost, 97). Often growers wit two yers before they strt hrvest, but more growers re tking some hrvest erlier (1 st yer) to offset the high cost of crop estblishment. There is some very good evidence tht erly hrvests (Wilson, 99) nd excessive hrvest pressure (Peterson, 25) contribute to erly decline in sprgus plntings. It is lso importnt to know tht there is limited new root nd bud growth until fter hrvest nd most of this occurs in July nd August (Drost, 97; Wilcox-Lee, 91). Since sprgus productivity depend on the plnts bility to blnce root nd crown growth in summer nd sper growth during the spring hrvest (Drost, 99), more growers re now smpling plnts periodiclly to ensure tht root CHO levels re optimized. In 23, I outlined this progrm nd explined how it cn be used nd detiled the ccepted growth ptterns of plnt growth nd CHO utiliztion during the sesonl production cycle. Reserch indictes tht typicl sprgus plnt should hve 8-1 lrge fern tht weight 2-3 pounds (Wilson, 2). Ech plnt would lso hve severl hundred lrge storge roots tht weigh 8-1 pounds, nd hve 75 or more buds. At the beginning of the yer, storge roots should hve 45% or more of their weight stored s usble CHO s nd tht t the end of the yer, the plnt would be rechrged with CHO to this sme level. We would lso like to see uniformly distributed root system throughout the soil nd the plnt popultion should be greter thn 9% of the initil popultion. Fields like these hve the potentil for high yields. Wter Requirements While sprgus is considered drought tolernt plnt, mny studies show tht when supplied with dditionl wter during fern growth, productivity in the next yer improves (Drost, 1999). The timing of wter pplictions, nd the mount pplied cn significntly impct fern nd root development, bud number nd size, nd CHO storge. In most temperte production res, 2-3 inches of wter re

6 needed during the fern growth period. More importntly, recent work shows tht for young estblishing plnts, wter needs re more criticl since root size is smll nd distribution throughout the soil is shllow nd limited (Peterson, 5). In 22, we estblished n irrigtion study to ssess how irrigtion mounts (, 75 nd 15% of ET) nd ppliction system (drip or sprinkler) influenced sprgus growth nd yield (Peterson, 5). Tretments were pplied only during the fern growth period (June to September) strting the yer fter estblishment. Incresing the mount of wter pplied to sprgus during the summer hd significnt effect on fern number nd weight (Tble 1). There were more fern per plnt when sprgus ws irrigted t 15% ET thn t 75% ET t both smpling times. For plnts which were not irrigted, they hd less thn hlf the fern number of ferns compred to the 75% ET ppliction. Similr results were seen when compring fern dry weight. We noted tht over-irrigting cuses lte seson fern growth which hs been shown to lower yields the following spring due to reduction in CHO content nd bud number. Root growth in the 75 nd 15% ET plots ws not different but ws greter thn non-irrigted plots (Fig.1). Irrigtion method does impct sprgus productivity levels (Tble 2). Fern number were not different between the drip nd sprinkler irrigted plnts, but in most yers, fern dry weight ws greter when plnts were irrigted with drip. Greter numbers of fern per plnt nd fern dry weight does not lwys trnslte into higher levels of productivity (sper yield). Growers need to understnd tht fern growth must be blnced with root development nd crbohydrte storge. Our reserch in Uth(Fig. 2), nd in new sprgus plntings in Cliforni, nd Wshington hs shown tht there is better root growth nd yield improvement when fields re irrigted with drip compred to furrow or sprinkler systems. Much of this is due to better wter nd root distribution nd less lte seson fern growth. Sper yields responded to wter pplictions in both hrvest yers (Tble 3). There ws significnt reduction in yield when sprgus ws not irrigted in the previous growing seson. However, there ws no difference in yield between the 75 nd 15% ET tretments. While there ppers to be slight dvntge to using drip over sprinkler irrigtion, it is still too erly to determine if this is rel effect or just prt of the nturl vribility often noted in sprgus yield trils. We pln on continuing this study for two more yers. Is Irrigtion Necessry for Mid-Western Asprgus Growing Ares? To ddress this question it is necessry to know if sprgus plnts re subject to drought stress conditions during criticl times of the yer or if they re exposed to excessive mounts of wter tht cn lso ffect plnt productivity. Reserch in Germny hs shown tht wter dditions during the summer hd significnt impct on productivity in subsequent yers (Hrtmnn, 9). Their climtic conditions (tempertures nd rinfll) nd production conditions (soils) re not too dissimilr to Michign nd suggest tht similr results my occur here. It is importnt to time those wter pplictions to specific time periods in the plnts growth cycle nd to meet locl environmentl needs. If one looks t the published sprgus production figures for Michign nd reltes tht informtion to the precipittion dt from the previous growing seson, severl things become pprent. First, dry wether during June nd July my be influencing bud initition nd sizing. Second, wet wether in August or September cn stimulte dditionl fern growth which uses up buds tht could be next yer s spers. Third, more uniform moisture throughout the summer nd erly utumn cretes better conditions for bud initition nd sizing, while minimizing new fern growth. Finlly, dry conditions in September cn encourge erlier plnt dormncy nd CHO re-mobiliztion to the roots further contributing to better productivity in the next production seson. These effects will be demonstrted nd relted to the sesonl growth ptterns. Conclusions Successful sprgus production is bsed on blncing plnt growth dynmics with sper hrvest. It is becoming clerer tht culturl prctices erly in the life of plnting hve long-term effects on productivity. Until recently, growers hve only been ble to ssess the helth nd qulity of the fern. With the relese of AspireUS, growers now cn monitor root CHO levels which give better ssessment of

7 how the plnt is responding to frm mngement decisions. Continued work on the role the root plys in crop productivity should help us further understnd root/fern reltionships nd future productivity. Cittions Drost, D. 1997: Asprgus. p In: HC Wien (ed.), The Physiology of Vegetble Crops. CAB Interntionl, Wllingford, United Kingdom. Drost, D. 1999: Irrigtion effects on sprgus root distribution. Act Horticulture 479: Dufult, RJ; Greig, JK. 1983: Dynmic growth chrcteristics in seedling sprgus. Journl of the Americn Society for Horticulturl Science 18: Hrtmnn, H.D., G. Hermnn, nd R. Kirchner-Neb Einfluß der Witterung während der Vegettionszeit uf den nächstjährigen Ertrg von Sprgel. (The influence of climtic conditions in the growing seson on the yield of sprgus in the subsequent yer). Grtenbuwissenschft 55:3-34. Peterson, RS. 25. Evluting sprgus productivity by ssessing frm prctices, irrigtion methods, nd hrvest pressure. MS Thesis. Uth Stte University. Wilcox-Lee, D; Drost, D. 1991: Tillge reduces yield nd crown, fern, nd bud growth in mture sprgus plnting. Journl of the Americn Society for Horticulturl Science 116: Wilson, DR; Sinton, SM; Wright, CE. 1999: Influence of time of sper hrvest on root system resources during the nnul growth cycle of sprgus. Act Horticulture 479: Wilson, DR; Cloughley, CG; Jmieson, PD; Sinton, SM. 22: A model of sprgus growth physiology. Act Horticulture 589: Tble 1. Effect of different irrigtion ppliction mounts (% ET) on fern number nd dry weight t the end of the growing sesons. % Evpo- Fern number/plnt Fern dry weight (g) trnspirtion Sign. * * * * Tble 2. The influence of irrigtion system on fern number nd dry weight t the end of the growing sesons. Irrigtion Fern number/plnt Fern dry weight (g) System Not wtered Drip Sprinkler Sign. * ns * * Tble 3. Effect of different irrigtion mounts (% ET) nd irrigtion systems on sper yield (pounds/cre) during hrvest sesons. % Evpotrnspirtion Totl Yield (lb/a) Irrigtion System Totl Yield (lb/a) Not wtered Drip Sprinkler Sign. * * * * Yield in 23 before ppliction of irrigtion tretments ws 76 lb/a

8 Figure 1. Asprgus root distribution in 24 s influenced by irrigtion mounts. Root biomss ws 6.64, 17.95, nd pounds per plnt (fresh weight) for the, 75 nd 15% ET irrigted plnts, respectively. % Distnce % ET Distnce (cm) % ET Distnce (cm) g / cm^3-1 g / cm^3 g / cm^ m ) ( c - 4 h e pt D - 5 Depth (cm) Depth (cm) Figure 2. Asprgus root distribution in 24 s influenced by irrigtion system. Root biomss ws 6.64, 13.13, nd pounds per plnt (fresh weight) for the non-, sprinkler, nd drip irrigted plnts. Non-Irrig Sprinkler Drip Distnce Distnce Distnce g / cm^3-1 g / g / m ) ( c - 4 h D e pt m ) ( c - 4 h e pt D m) -4 D ep t h ( c