Physical & Cultural Control of Pear Psylla

Physical & Cultural Control of Pear Psylla Psylla Summit 22-23 September, 2014 Fruit Commission, Yakima, WA Elizabeth H. Beers Tree Fruit Research & Extension Center 1100 N. Western Ave. Wenatchee, Washington

Is Pear Psylla an Induced Pest? Key Pest: one that will continue to cause economic damage in the absence of all pesticides Induced Pest: one that will cease to reach damaging levels once pesticides are withheld

10-year study of discontinued sprays 1 acre orchard, isolated, no insecticides or acaricides 1960-1969 ERM not a problem CM, PC, RBLR and AM rendered the crop worthless after the 1st year. LAW caused severe fruit injury during last 2 year (took 8 years to show up!!!) AM consistently most damaging pest, generally >75% damage Glass, E. H., and S. E. Lienk. 1971. Apple insect and mite populations developing after discontinuance of insecticides: 10-year record. J. Econ. Entomol. 64: 23-26.

Is Psylla an Induced Pest? Orchards that had received no chemical spray applications for a number of years showed only trace numbers of both the pear psylla and its predators. Apparently when biological control of the psylla is achieved, very few predators suffice to maintain it. #10002. Watson, T. K., and W. H. A. Wilde. 1963. Laboratory and field observations on two predators of the pear psylla in British Columbia. Can. Entomol. 95: 435-438. The trees at this orchard had received all cultural requirements except the application of pesticides. The orchard suffered heavily from pear psylla attack from 1959 through 1961. In 1962 predators (anthocorid bugs and lacewings) brought the pear psylla population to a low level. #10003. Madsen, H. F., and T. T. Y. Wong. 1964. Effects of predators on control of pear psylla. Calif. Agric. 18: 2-3.

Tree Washes Brunner & Burts 1981 5 unreplicated plots, 50 trees, 10x20ft, 0.23 acres cv. Bartlett Measured nymph density throughout season Measured honeydew 4x in July/Aug Measured fruit damage at harvest #9991. Brunner, J. F., and E. C. Burts. 1981. Potential of Tree Washes as a Management Tactic Against the Pear Psylla. J. Econ. Entomol. 74: 71-74.

Tree Washes Brunner & Burts 1981 (Wash volume 1,000 to 1,200 gpa, applied handgun dormant DD Washes Unwashed x x 13-Mar 4-Apr 10-Jun 17-Jun 25-Jun 2-Jul 9-Jul 15-Jul 21-Jul 28-Jul 2 washes + Triton x x x x 6 washes + Triton x x x x x x x 8 washes, water only x x x x x x x x x Unwashed x #9991. Brunner, J. F., and E. C. Burts. 1981. Potential of Tree Washes as a Management Tactic Against the Pear Psylla. J. Econ. Entomol. 74: 71-74.

12000 Nymphs 10000 Nymph-days (cum) 8000 6000 4000 2000 Mean honeydew (mg fructose/50 lvs) 4 samples 70 60 50 40 30 20 10 0 0 Unwashed Honeydew Unwashed 2 washes water+triton 2 washes water+triton 6 washes water+triton 6 washes water+triton 8 washes water only 8 washes water only Unwashed Unwashed Tree Washes Brunner & Burts 1981 #9991. Brunner, J. F., and E. C. Burts. 1981. Potential of Tree Washes as a Management Tactic Against the Pear Psylla. J. Econ. Entomol. 74: 71-74.

Overtree irrigation Westigard et al 1979 Measured codling moth, psylla, TSM, rust mite 3-year study, 1976-1978 Bartlett, d Anjou Overtree vs undertree, 3 replicated blocks 5-6 irrigations, biweekly, 75 mm (3 inches) in 24 h Standard CM spray program Results: CM no difference in OT vs UT PP significantly lower in OT in 2 of 3 years PRM significantly lower in OT in 1 year (only 1 measured) TSM no difference in the 2 years this was measured PP natural enemies no difference, 1 out of 1 year measured #10010. Westigard, P. H., P. B. Lombard, and R. B. Allen. 1979. Effects of Overtree Irrigation on Density and Damage of Pear Pests. J. Econ. Entomol. 72: 839-840.

Effect of Abiotic factors Ross 1918: High temps + low humidity cause decline in pear psylla populations Wilde 1965: Drenching rains (2 inches) dislodged instars 1-4; eggs remained attached. Wilde 1965: exposure of liquid honeydew in lab experiments to 114-117 F/30% RH did not solidify the honeydew. Madsen 1962: speculated that in coastal CA, temps above 32.2 C [90 F] restrict egg laying. #9991. Brunner, J. F., and E. C. Burts. 1981. Potential of Tree Washes as a Management Tactic Against the Pear Psylla. J. Econ. Entomol. 74: 71-74.

Effect of Temp/Vigor on Fecundity McMullen & Jong 1972 250 Fecundity Eggs/female 200 150 100 50 ab June August August ab b c d bc Summerland BC cv. Bartlett June = cool (18 C) August = hot (25 C) Field clip cages of females, lifetime fecundity Vigorous v non-vigorous orchards 0 Nonvigorous/18 C Vigorous/18 C Nonvigorous/25.1 C Vigorous/25.1 C Non-vig to vig/25.1 C Vig to non-vig/25.1 C #10004. McMullen, R. D., and C. Jong. 1972. Influence of temperature and host vigor on fecundity of the pear psylla (Homoptera: Psyllidae). Can. Entomol. 104: 1209-1212.

Effect of Nitrogen fertilization Pfeiffer & Burts 1983 Mature d Anjou orchard (Smith Tract 7?) 4 trts of N rates and timing, 2x2 factorial Treatments applied 4 years, data taken 1 year Rate of N per acre Timing 77 lb 108 lb Dormant 77 lb, 108 lb, dormant dormant Late Summer 77 lb, late summer 108 lb, late summer

Effect of Nitrogen fertilization Pfeiffer & Burts 1983 Higher N rates produced higher levels of psylla (egg, nymphs Timing had little effect (interaction NS) Early season populations most affected

Effect of N on psylla predators Daugherty et al 2007 Hypothesis: plant quality mediates the efficacy of an important natural enemy of pear psylla, Anthocoris nemoralis Potted, caged 1-yr-old Bartlett trees Fertilized with high or low rates of N (Hoaglands, 5 vs 20 mm N)* Added psylla alone, or psylla+predator Measured plant growth, psylla density, predators E. *the Beers low level 2014 was characterized as limiting to plant growth #10008. Daugherty, M. P., C. J. Briggs, and S. C. Welter. 2007. Bottom-up and top-down control of pear psylla (Cacopsylla pyricola): Fertilization, plant quality, and the efficacy of the predator Anthocoris nemoralis. Biol. Contr. 43: 257-264.

Effect of N on psylla predators Daugherty et al 2007, cont d More N=bigger trees with higher N content More N=more psylla Level of suppression by Anthocoris not related to N level, but was related to psylla density Prior to predator additions

Vigor suppression by PGRs Westigard et al 1980 % Downgraded Fruit from Psylla 14 12 10 8 6 4 2 0 Fruit Damage 1977 1978 1979 Alar Check Daminozide (Alar) at 2000 ppm AI 18 yr old Bartlett 5 single-tree reps 3-year study, 1977-1979 Timed for 7-9 leaves of new shoot growth (30-50 DAFB) #892. Westigard, P. H., P. B. Lombard, R. B. Allen, and J. G. Strang. 1980. Pear Psylla pyricola: population suppression through host plant modification using daminozide. Environ. Entomol. 9: 275-277.

Vigor suppression by PGRs Paulson et al 2005 Psylla nymphs/leaf 20 15 10 5 Psylla Nymphs Apogee 3x Imidacloprid+Apogee Imidacloprid Check 0 12-May 19-May 26-May 02-Jun 09-Jun 16-Jun 23-Jun 30-Jun Prohexadione calcium (Apogee) 4 trts, Apogee with or without Imidacloprid + Control Bartlett 21 yr old 4 single-tree reps 1-year study, 1999 Measured nymph, adult density (May-June only); shoot growth #10007. Paulson, G. S., L. A. Hull, and D. J. Biddinger. 2005. Effect of a Plant Growth Regulator Prohexadione-Calcium on Insect Pests of Apple and Pear. J. Econ. Entomol. 98: 423-431.

Fertization, PGRs Shaltiel-Harpaz et al 2010 Cacopsylla bidens (Sulc), Israel Manipulated N levels and PGRs (Clormequat chloride and Apogee) Three levels of N: 0, 50, 100 ppm N via drip irrigation Potted, field grown trees, treated 8 mo before start of exp. Higher oviposition and nymph development rates in trees with higher leaf N PGRs suppressed growth even in trees with high N level #10011. Shaltiel-Harpaz, L., R. Kedoshim, D. Openhiem, R. Stern, and M. Coll. 2010. Effect of host plant makeup through nitrogen fertilization and growth regulators on the pear psylla population. Israel Journal of Plant Sciences 58: 149-156.

Effect of Cultivar PP nymph densities were higher on Anjou than on Bartlett or Flemish Wilde, 1962 #7245. Wilde, H. A. 1962. Bionomics of the pear psylla, Psylla pyricola Foerster in pear orchards of the Kootenay valley of British Colombia, 1960. Can. Entomol. 94: 845-849.

Effect of Ground Cover Management PP increased more rapidly in a clean cultivated plot than in a plot with cover crop. [Clean cultivated plots had higher temperature and lower humidity]. Cover cropped plots harbored more natural enemies Wilde, 1962 #7245. Wilde, H. A. 1962. Bionomics of the pear psylla, Psylla pyricola Foerster in pear orchards of the Kootenay valley of British Colombia, 1960. Can. Entomol. 94: 845-849.

Practices to reduce vigor Minimize N fertilization Pruning practices/type of cuts, timing Tree training Tree density/spacing Rootstocks/interstems/cultivar Root pruning Plant growth regulators

Bins/acre (bin=1,100 lb) 44 42 40 38 36 34 32 30 28 Yield - winter pears Economic Health Washington winter pears 26 24 2002 2004 2006 2008 2010 2012 2014 360 340 320 $/bin - winter pears 300 280 $/bin 260 240 220 200 180 160 140 2002 2004 2006 2008 2010 2012 2014