1. Potato Leafhopper-Resistant Alfalfa- 2002 Update J. L. Hansen 1, J. Keith Waldron 2, and D.R. Viands 1 1 Dept. Of Plant Breeding; 2 NYS IPM Program- Livestock & Field Crops 2 NYS IPM Program - Livestock & Field Crops Cornell University - Ithaca, NY CAIC Virtual Meeting, 7/2003

2. Potato Leafhopper in Alfalfa Potato leafhopper (PLH), is the most damaging insect pest of alfalfa, Medicago sativa L., in midwestern and eastern states (Manglitz and Ratcliffe, 1988).

3. Migration PLH over-winter in southern regions of the US and migrate northward on spring storms. PLH populations can be expected on alfalfa in New York from mid-June through August. Newly planted seedings are at highest risk of damage.

4. Potato Leafhopper Resistant Alfalfa The PLH resistance (glandular hairs) was developed from a wild species of alfalfa and transferred into conventional alfalfa through traditional plant breeding techniques

5. Potato leafhopper resistant (dark green plots) and susceptible (light green plots) alfalfa in a spring-seeded plot trial prior to first harvest.

6. Plot trials comparing PLH-resistant and susceptible alfalfa cultivars and experimentals have been planted in New York every year since 1996. Results from trials planted in 1997 through 2000 are in: J. Hansen et al, Crop Science 42:1155-1163

7. PLH Resistant Alfalfa – Summary of Results from 1997-2000 PLH-resistant alfalfa cultivars and experimentals sustained significantly less visible PLH damage, sustained significantly less visible PLH damage, supported fewer nymphs and adult PLH, supported fewer nymphs and adult PLH, had higher crude protein concentration, and had higher crude protein concentration, and matured earlier matured earlier than susceptible cultivars and experimentals.

8. PLH Resistant Alfalfa – Summary of Results from 1997-2000 Early generation PLH-resistant cultivars did not provide complete and adequate protection against yield loss due to PLH.Early generation PLH-resistant cultivars did not provide complete and adequate protection against yield loss due to PLH. However, PLH-resistant cultivars and experimentals consistently yielded more than PLH-susceptible cultivars at the first harvest of the first production year, following severe PLH damage in the seeding year.However, PLH-resistant cultivars and experimentals consistently yielded more than PLH-susceptible cultivars at the first harvest of the first production year, following severe PLH damage in the seeding year.

9. PLH Resistant Alfalfa – Conclusions from 1997-2000 When insecticides were not used to control PLH, first generation PLH-resistant cultivars provided benefits such as higher percent crude protein, less hopperburn, and higher forage yield at first harvest in the year following severe PLH damage during the seeding year. However, until total season yields of PLH-resistant alfalfa cultivars equal or exceed the yields of conventional alfalfa cultivars, PLH-resistant alfalfa cultivars will likely represent only a small to moderate percentage of total alfalfa seed sales. However, until total season yields of PLH-resistant alfalfa cultivars equal or exceed the yields of conventional alfalfa cultivars, PLH-resistant alfalfa cultivars will likely represent only a small to moderate percentage of total alfalfa seed sales.

10. PLH Resistant Alfalfa – 2002 In 2002, four trials of PLH-resistant and susceptible alfalfa experimentals and cultivars were harvested. The following slides summarize data from no- insecticide trials harvested in 2002. The objective of this study was to compare later- generation PLH-resistant alfalfa cultivars and experimentals (planted in 2001 and 2002) with early- generation PLH-resistant alfalfa cultivars and experimentals (planted in 1999 and 2000) for yield and PLH damage.

11. Trial Cultivars and Experimentals 54H69 – 199954H69 – 1999 53H81 – 199953H81 – 1999 DK121 HG – 1999DK121 HG – 1999 4R37 – 1999, 20004R37 – 1999, 2000 DK131 HG – 1999DK131 HG – 1999 ABT 227 LH – 1999ABT 227 LH – 1999 Freedom – 1999Freedom – 1999 Clean Sweep 1000 – 1999Clean Sweep 1000 – 1999 3A10 – 20003A10 – 2000 ZH 9840 H – 2000ZH 9840 H – 2000 ZH 9841 H – 2000ZH 9841 H – 2000 Seedway LH 3000 – 2001, 2002Seedway LH 3000 – 2001, 2002 Pegasus – 2001, 2002Pegasus – 2001, 2002 54H91 – 200254H91 – 2002 HYTEST 340 PLH - 2002HYTEST 340 PLH - 2002 Trophy – 1999Trophy – 1999 5312 – 1999, 2000, 2001, 20025312 – 1999, 2000, 2001, 2002 Cimarron SR – 1999Cimarron SR – 1999 53Q60 – 199953Q60 – 1999 Oneida VR – 1999, 2000, 2001, 2002Oneida VR – 1999, 2000, 2001, 2002 Vernal – 1999, 2000, 2001, 2002Vernal – 1999, 2000, 2001, 2002 Alfagraze – 1999Alfagraze – 1999 HayGrazer – 2000HayGrazer – 2000 Du 299 – 2000Du 299 – 2000 Key – 2000Key – 2000 Paragon BR – 2001Paragon BR – 2001 DU 200 – 2001DU 200 – 2001 GPVL44 – 2002GPVL44 – 2002 CK2000 - 2002CK2000 - 2002 PLH-Resistant, Year Planted PLH-Susceptible, Year Planted

12. PLH Resistant Alfalfa – 2002 Caveats Data over trials are confounded by field, year of planting, and entries.Data over trials are confounded by field, year of planting, and entries. A small number of later-generation PLH- resistant cultivars have been tested.A small number of later-generation PLH- resistant cultivars have been tested.

13. Number of PLH-Resistant alfalfa cultivars entered in Cornell Forage Yield Testing Program 1997-2002 dropped after release of first generation cultivars. No. of PLH-% of Total YearResistant EntriesNo. of Entries 1997825 19981337 1999413 20002 experimentals5 20012 cultivars10 20022 cultivars10

14. PLH Resistant Alfalfa – 2002 Data for each of four trials are presented in the next four slides. In Production year trials: Early generation PLH-resistant cultivars and experimentals had an average PLH damage score of 3.4.Early generation PLH-resistant cultivars and experimentals had an average PLH damage score of 3.4. Later generation PLH-resistant cultivars had an average PLH damage score of 1.4.Later generation PLH-resistant cultivars had an average PLH damage score of 1.4. PLH damage score: 1=almost no damage; 5=severe PLH damage

15. 1999 Trial harvested in 2002 – early generation PLH- resistant cultivars and experimentals Yield Data – 2002 Total % of PLH 17Jun5Aug17SepSeason TrialDamage% Stand - - - - tons/acre dry matter - - - Average8/5/200210/4/2002 Avg. of 8 Res. 2.701.840.575.10 99 3.5 88.8 Entries Avg. of 7 Sus.2.871.660.635.16 101 5.0 91.1 Entries Res. Vs Sus.-0.18**+0.18**-0.06**-0.05 ns-1.4**-2.4** *, ** = statistically significant at P<0.05 and 0.01 respectively; ns=not statistically significant. PLH damage score: 1=none 5=severe. PLH-resistant trial entries had significantly higher forage yield than PLH-susceptible entries at second harvest, and had lower forage yield at first and third harvest. at first and third harvest.

16. 2000 Trial harvested in 2002 – early generation PLH- resistant experimentals Yield Data – 2002 Total % of PLH 18Jun9Aug19SepSeason TrialDamageNo. Nymphs - - - - tons/acre dry matter - - - Average8/8/20028/8/2002 Avg. of 4 Res. 3.682.310.676.68 104 3.4 28 Entries Avg. of 6 Sus.3.692.020.656.36 99 4.8 36 Entries Res. Vs Sus.-0.01ns+0.29**+0.02ns+0.32**-1.4**-8ns *, ** = statistically significant at P<0.05 and 0.01 respectively; ns=not statistically significant. PLH damage score: 1=none 5=severe. No. of nymphs per 10 stems averaged over 3 replications. PLH-resistant trial entries had significantly higher forage yield than PLH-susceptible entries at second harvest, but had comparable forage yield at first and third harvests.

17. 2001 Trial harvested in 2002 – later generation PLH- resistant cultivars Yield Data – 2002 Total % of PLH No. PLH 24Jun8Aug7SepSeason TrialDamageper 5 sweeps - - - - tons/acre dry matter - - - Average8/2/20027/30/2002 Avg. of 2 Res. 3.051.600.765.40 105 1.4 7 Entries Avg. of 5 Sus.2.691.650.644.98 96 4.8 75 Entries Res. Vs Sus.+0.36**-0.05ns+0.12**+0.42**-3.4**-68** *, ** = statistically significant at P<0.05 and 0.01 respectively; ns=not statistically significant. PLH damage score: 1=none 5=severe. PLH-resistant trial entries had significantly higher total season forage yield than PLH-susceptible entries as a result of higher first harvest yield after severe PLH damage in seeding year.

18. 2002 Trial harvested in 2002 – later generation PLH- resistant cultivars Yield Data – 2002 Total% of PLH 21Jul5SepSeasonTrial Damage% Stand - - tons/acre dry matter - - Average7/21/20029/24/2002 Avg. of 4 Res. 0.490.561.06132 3.2 97.1 Entries Avg. of 5 Sus.0.170.410.5873 5.0 94.7 Entries Res. Vs Sus.+0.32**+0.16**+0.48**-1.8**+2.4ns *, ** = statistically significant at P<0.05 and 0.01 respectively; ns=not statistically significant. PLH damage score: 1=none 5=severe. PLH-resistant trial entries had significantly higher total season forage yield than PLH-susceptible entries in the seeding year.

19. PLH Resistant Alfalfa – Trends and Observations from 2002 Although only two later-generation PLH-resistant cultivars were available for testing, in 2002 these cultivars were clearly superior in resistance and forage yield to early-generation PLH-resistant cultivars.Although only two later-generation PLH-resistant cultivars were available for testing, in 2002 these cultivars were clearly superior in resistance and forage yield to early-generation PLH-resistant cultivars. Although more PLH-resistant cultivars need to be tested for more production years, it seems likely that PLH-resistant cultivars on the market now are comparable in forage yield to conventional cultivars.Although more PLH-resistant cultivars need to be tested for more production years, it seems likely that PLH-resistant cultivars on the market now are comparable in forage yield to conventional cultivars.

20. PLH Resistant Alfalfa – Trends and Observations from 2002 Crop monitoring is still recommended to collect crop and pest status information on which to base sound management decisions.Crop monitoring is still recommended to collect crop and pest status information on which to base sound management decisions. PLH-resistant cultivars do not generally need to be sprayed to control PLH with the exception of very high PLH populations during the seeding year.PLH-resistant cultivars do not generally need to be sprayed to control PLH with the exception of very high PLH populations during the seeding year. Economic thresholds adjusted for managing PLH in PLH- resistant alfalfa are not currently available.Economic thresholds adjusted for managing PLH in PLH- resistant alfalfa are not currently available. Seeding year PLH-resistance improvements are needed.Seeding year PLH-resistance improvements are needed. Producers should not hesitate to try planting these later- generation PLH-resistant cultivars.Producers should not hesitate to try planting these later- generation PLH-resistant cultivars.

21. PLH Resistant Alfalfa – UNEXPLAINABLE Trends and Observations Visual differences in yield between resistant and susceptible cultivars at times did not translate into yield differences in tons per acre dry matter.Visual differences in yield between resistant and susceptible cultivars at times did not translate into yield differences in tons per acre dry matter. Pioneer 5312, a susceptible cultivar used as a check in all four trials, had yield comparable to resistant cultivars in spite of heavy PLH damage in the three production year trials (105% of total season average in 1999, 109% of total season average in 2000, 102% of total season average in 2001).Pioneer 5312, a susceptible cultivar used as a check in all four trials, had yield comparable to resistant cultivars in spite of heavy PLH damage in the three production year trials (105% of total season average in 1999, 109% of total season average in 2000, 102% of total season average in 2001).

22. J. Keith Waldron New York State Integrated Pest Management Program Livestock and Field Crops IPM NYS Agricultural Experiment Station 630 W. North St., Geneva, NY 14456 jkw5@cornell.edu Julie Hansen Department of Plant Breeding Forage Breeding Project 101 A Love Lab Cornell University Ithaca, NY 14853 jlh17@cornell.edu For Further Information on this Project Contact:

23. New York State Integrated Pest Management Program http://www.nysipm.cornell.edu Forage Breeding Project at Cornell University www.plbr.cornell.edu/pbbweb/foragetest

24. References Hansen, J.L., J.E. Miller-Garvin, J.K. Waldron, and D.R. Viands. 2002. Comparison of potato leafhopper-resistant and susceptible alfalfa in New York. Crop Sci. 42:1155-1163. Manglitz, G.R., and R.H. Ratcliffe. 1988. Insects and Mites. In A.A. Hanson et al. (ed.) Alfalfa and alfalfa improvement. Agronomy 29:671-704. McCaslin, M., and D. Miller. 1998. Potato leafhopper resistance. In C.C. Fox et al. (ed.) Standard tests to characterize alfalfa cultivars. North Amer. Alfalfa Improv. Conf., Beltsville, MD. p. I-7.