Soybean Cyst Nematode: a Continually Growing Problem in Soybeans?

Transcription

1 Soybean Cyst Nematode: a Continually Growing Problem in Soybeans? X Greg Tylka Iowa State University Department of Plant Pathology and Microbiology January 31 & February 1, 2017

2 cyst (dead female) full of eggs female+eggs Tylka Tylka eggs Tylka ~24 days per generation 3-6 generations per year >200 eggs per female eggs can survive >10 years dormant in soil adult female and male mating occurs on root Baum juveniles adult male swollen juvenile adult female Tylka Tylka Tylka

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4 Challenges for the Future SCN continues to spread

5 Known SCN-Infested Counties Feb. 2014

6 Known SCN-Infested Counties Feb North new Dakota: since 2014: Alabama Bensen = 1 Georgia Cavalier = 3 Indiana Foster = 1 Iowa McIntosh = 1 Kansas Rolette = 2 Kentucky Stutsman = 3 Minnesota Walsh = 2 South Missouri Dakota: = 1 N. Campbell Carolina = 4 N. Dakota = 7 Minnesota: Ohio = 3 S. Ladena Dakota = 1 Virginia Lake of the = 2 Woods Wisconsin = 1 Quebec = 1

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8 How Does SCN Spread? anything that moves soil wind-blown soil water-eroded soil wildlife field equipment tare soil

9 Challenges for the Future SCN continues to spread lack of symptoms

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11 SCN Eggs / 100 cc Soil Yellow plants Soybean Yield (bu/acre)

12 Dig roots and look for females

13 Dig roots and look for females SCN females

14 Collect soil samples to test for SCN

15 Challenges for the Future SCN continues to spread lack of symptoms selection of resistant varieties

16 field infested with SCN Photo: University of Minnesota susceptible soybean variety resistant soybean variety

17 field infested with SCN Richland Co., ND susceptible soybean variety resistant soybean variety Photos: B. Nelson, North Dakota State University

18 Yield and SCN Control SCN-resistant vs Susceptible Soybean Varieties East Central Iowa (1,310 eggs/100 cm 3 at planting) 52.7 bushels per acre 45.9

19 Yield and SCN Control SCN-resistant vs Susceptible Soybean Varieties East Central Iowa (1,310 eggs/100 cm 3 at planting) bushels per acre 52.7 $ ,169 8,875 10,000 8,000 6,000 4,000 2,000 eggs per 100 cm 3 soil at harvest 0 SCN

20 Number of SCN-resistant Soybean Varieties Available for Iowa (MG 0-3) Number of varieties

21 Companies with SCN-resistant Soybean Varieties for Minnesota & North Dakota a few per company several per company Source: S. Markell, North Dakota State University

22 Challenges for the Future SCN continues to spread lack of symptoms selection of resistant varieties lack of resistance diversity in soybeans

23 Registered Germplasm Lines that are Sources of SCN Resistance for Breeding PI (Peking) PI PI PI PI PI PI (Cloud) Many other breeding lines with different sources of resistance to SCN identified and released by breeders as well. The ability of SCN populations to reproduce on resistant sources determined with the HG type test.

24 Number of SCN-resistant Soybean Varieties Available for Iowa (MG 0-3) Number of varieties PI Other Can you guess which source of resistance is not very effective in Iowa any more?? PI Why will seed companies not develop more varieties with other sources of resistance?? $0.00

25 Challenges for the Future SCN continues to spread lack of symptoms selection of resistant varieties lack of resistance diversity in soybeans some dry beans are good hosts for SCN

26 Female index SCN Reproduction on Dry Bean in the Greenhouse Buster GTS-900 Maverick PINTO NAVY Othello Rally Remington Topaz Winchester Cirrus Ensign Mayflower Navigator Norstar Premiere Seahawk Vista Cal Early KIDNEY Percent of SCN females on a plant relative to the number on a susceptible a soybean. Source: S.H. Poromarto and B.D. Nelson, North Dakota State University Susceptible soybean BLACK Chinook Montcalm Red Hawk T-39 Condor Jaguar Eclipse Lee 74

27 Prospects for the Future SCN will continue to spread and thrive in MN, ND, and SD obvious symptoms will not occur for years after initial infestation detecting SCN infestations before symptoms become obvious is a unique management opportunity it s easier to keep low SCN numbers low than it is to drive high numbers back down

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29 Prospects for the Future growing SCN-resistant soybean varieties with PI will likely produce profitable yields in ND, MN, and SD for some time growing nonhost crops will be the primary means of reducing SCN population densities (5 to 50% annually) but reduces only for 2 or 3 years

30 Effects of Continuous Corn on SCN Population Densities in Iowa End-of-season SCN numbers (eggs/100 cc soil) soybeans 1st year 2nd year 3rd year corn corn corn

31 Effects of Continuous Wheat on SCN Population Densities in North Dakota * = susceptible Source: B.D. Nelson, North Dakota State University

32 Prospects for the Future growing SCN-resistant soybean varieties with PI will likely produce profitable yields in ND, MN, and SD for some time growing nonhost crops will be the primary means of reducing SCN population densities (5 to 50% annually) but reduces only for 2 or 3 years nematode-protectant seed treatments are a muchneeded addition to the toolbox, but are not a replacement for resistant soybean varieties

33 Prospects for the Future growing SCN-resistant soybean varieties with PI will likely produce profitable yields in ND, MN, and SD for some time growing nonhost crops will be the primary means of reducing SCN population densities (5 to 50% annually) but reduces only for 2 or 3 years nematode-protectant seed treatments are a muchneeded addition to the toolbox, but are not a replacement for resistant soybean varieties effects of cover crops on SCN population densities is not yet well documented

34 Questions? Comments?