NEW APPROACHES TO CONTROL DISEASES IN ONIONS AND POTATOES Mike Thornton Parma R& E Center Potato Program of Distinction
OUTLINE Disease control in onions with drip application of Fontelis Control of the potato early die complex with biological pesticides
BACKGROUND - Pink root is caused by the soil born fungus Phoma terrestris. - Inoculum survives for long periods in soil, and pathogen has a wide host range = rotation is moderately effective. - Soil temperatures above 70F are optimum for infection. - Host resistance and fumigation are primary means of control.
RELATIONSHIP OF PINK ROOT SEVERITY TO YIELD IN ONIONS 100 90 80 Yield (t/ha) 70 r = -0.648* 60 50 40 0 10 20 30 40 50 60 Incidence of severe infection (%) Source: Thornton and Mohan, 1996
RELATIONSHIP BETWEEN FUMIGATION RATE AND PINK ROOT
TWO-YEAR FIELD TRIAL Compare pink root control of Chloropicrin to Fontelis Penthiopyrad (Group 7 fungicide) 2ee label for pre and post-plant applications for suppression of pink root Trials have evaluated in-furrow applications, few drip injection trials
2000 2001 2002 2330 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Acres under drip Used on ~65% of onion acreage in the Treasure Valley 16000 14000 12000 10000 8000 6000 4000 2000 0 (50% of acres)
Treatments Treatment Rate applied Timing Strike CP^ 4 gal Fall Fontelis (early)* 24 oz 2 leaf Fontelis (early + late) 24 oz 24 oz 2 leaf July 1 Control -- -- ^55 lbs/ac active ingredient *0.3 lbs/ac active ingredient
Movement of soil mobile vs soil binding compounds Tape was here Photo Courtesy of DuPont Both dyes highly soluble, red dye binds to the soil
Number of bulbs PINK ROOT RATING 80 70 Incidence 60 50 40 Severity 30 20 10 0 None Slight Moderate Severe (1 to 10%) (11 to 50%) (51 to 100%) Rating category
Relative yield (% of control) RELATIONSHIP BETWEEN PINK ROOT AND YIELD 225 200 175 150 125 R² = 0.9508 100 75 50 R² = 0.6967 0 20 40 60 80 100 Pink root severity (% of bulbs rated severe)
Severity (% of bulbs) Total Yield (cwt/ac) SIGNIFICANT TREATMENT BY YEAR INTERACTIONS 100 c 900 800 a 75 50 25 0 a Non-treated Check 2015 2016 d d Strike CP (4 gal) 700 600 500 400 300 200 100 0 b c Non-treated Check 2015 2016 b Strike CP (4 gal)
Severity (% of bulbs) Total Yield (cwt/ac) COMPARISON OF FUMIGATION TO FONTELIS (MEANS OF 4 REPLICATIONS OVER 2 YEARS) 75 50 a b (18%) 800 700 600 500 400 b a (51%) b (3%) 25 300 0 (88%) Non-treated Check Strike CP (4 gal) Fontelis (24 oz)* c 200 100 0 Non-treated Check Strike CP (4 gal) Fontelis (24 oz)* * Applied via drip at 2 leaf stage
Total yield (cwt/ac) CAN FUMIGATION AND FONTELIS BE COMBINED? (2016 only) 700 4 gal rate 3 gal rate ab 600 ab 500 c bc 400 300 d 200 100 0 Non-treated Check Strike CP Strike CP + Fontelis Strike CP Strike CP + Fontelis
Severity (% of bulbs) IS MORE THAN ONE APPLICATION NEEDED? (means of 4 replications over 2 years) 75 a b b 50 25 0 Non-treated Check Fontelis Early Fontelis Early + Late
2009 SURVEY OF ONION GROWERS (> 90% FUMIGATED PRIOR TO ONIONS)
SHOULD WE RE-THINK HOW MUCH WE RELY ON FUMIGATION IN ONION PRODUCTION? + Breeding efforts are working + Drip irrigation reduces stress + Drip irrigation is lengthening rotations + Alternatives like Fontelis are available
ACKNOWLEDGEMENTS - Funding/ support provided by IEOOC, Dupont, Seminis and Allan Marks custom application
EARLY DIE COMPLEX Two main pathogens: Verticillium dahliae and Colletotrichum coccodes Root lesion nematode interaction (Pratylenchus sp.) Cause plants to wilt prematurely leading to decreases in yield and quality Large host range >200 Has cause yield losses as high as 50%
CONTROL MEASURES Crop rotation Sanitation Using certified seed Planting resistant varieties (Ranger Russet, Clearwater, Payette, etc) Fumigation (Metam sodium) Biological pesticides Source: http://spudsmart.com/soil-fumigation-potatoes/
BIOLOGICAL PESTICIDES Definition: Types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. Three types of biopesticides Microbial Plant-incorporated protectants (PIPs) Biochemical
MICROBIAL BIOPESTICIDES Contain microorganims such as bacteria, fungi, viruses, protozoa as biocontrol agents that can control pathogen and insect pests Source: http://organicsoiltechnology.com/bacillus-subtilis-bio-control.html
MODE OF ACTION Multiple modes of action: Direct Competition (space, nutrients) Antibiosis (antibiotics or other toxins) Predation Induced resistance Plant growth promotion Source: https://www.researchgate.net/publication/237091939_genetic_basis_of _mycoparasitism_a_mechanism_of_biological_control_by_species_of_trichode rma/figures?lo=1
ADVANTAGES Shorter re-entry and pre-harvest intervals Reduced risk to applicators and the environment Typically only affect target pathogens May be used as a component of IPM program
DISADVANTAGES Used as a preventative, not to cure disease Shorter shelf life and specific storing conditions May need to be applied multiple times Efficacy is not always consistent
Rhizoctonia incidence (%) Pink rot severity (%) RESEARCH OBJECTIVES Determine if microbial biopesticides provide economical/consistent control of the Early-die complex Determine the optimum application timing/method 35 30 25 20 15 10 5 0 Non-treated Maxim 4FS Maxim 4FS + Tenet 70 60 50 40 30 20 10 0 Wharton, 2012 Non-treated Resist 57 Serenade Soil Kirk, 2010
2016 & 2017 FIELD STUDIES Planted with cut certified Russet Norkotah seed Plots were 6 rows wide (18 ) by 40 long Included a non-treated check and a fumigated check (40 gal/ac metam sodium)
MATERIALS AND METHODS Serenade Soil (Bacillus subtilis QST 713) and Bio-Tam (Trichoderma asperellum and Trichoderma gamsii) In-furrow at planting and/or chemigated 4 times throughout the growing season beginning June 7th
MATERIALS AND METHODS Soil and stem samples were evaluated using a real-time polymerase chain reaction (qpcr) Visual symptoms of Verticillium wilt (Verticillium dahliae) were rated throughout June, July, and August. Conducted UAV flights to evaluate the normalized difference vegetation index (NDVI) as an indicator of the relative amount of live green vegetation in each plot Determined yield, tuber size and specific gravity at harvest
RAUDPC EARLY DIE SYMPTOMS 30 25 20 15 10 5 2016 2017 1 Non-treated 2 Fumigated check 3 Bio-Tam in-furrow (IF) 4 Bio-Tam chemigation - low rate (CL) 5 Bio-Tam IF + CL 6 Bio-Tam chemigation - high rate (HL) 7 Serenade in-furrow (IF) 8 Serenade chemigation - low rate (CL) 9 Serenade IF + CL 10 Serenade chemigation - high rate (HL) 0 1 2 3 4 5 6 7 8 9 10 *There were no significant differences among treatments
2016 FIELD STUDY-NDVI RESULTS
Verticillium dahliae DNA Colletotrichum coccodes DNA pg/g qpcr RESULTS Verticillium dahliae DNA Concentration Colletotrichum coccodes DNA Concentration 2000 18000 1800 1600 1400 1200 1000 800 600 400 200 16000 14000 12000 10000 8000 6000 4000 2000 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 Treatments Treatments *There were no significant differences among treatments
Yield (cwt/ac) YIELD RESULTS 700 650 600 550 500 450 2016 2017 1 Non-treated 2 Fumigated check 3 Bio-Tam in-furrow (IF) 4 Bio-Tam chemigation - low rate (CL) 5 Bio-Tam IF + CL 6 Bio-Tam chemigation - high rate (HL) 7 Serenade in-furrow (IF) 8 Serenade chemigation - low rate (CL) 9 Serenade IF + CL 10 Serenade chemigation - high rate (HL) 400 1 2 3 4 5 6 7 8 9 10 *There were no significant differences among treatments
SUMMARY/CONCLUSION Under our field conditions biological pesticides did not reduce early die symptoms Early die incidence was low to moderate Still more research needed to understand the mode of action and efficacy. Source: http://npic.orst.edu/envir/soil.html
1 Potato Early Die Trial Parma, ID on August 25, 2017 1 1 = Untreated check 13 = Serenade + Velum Prime 14 = Elatus 14 13 13 14 13 14 14 13 1 1
ACKNOWLEDGEMENTS Northwest Potato Research Consortium Nick Vincent Ransey Portenier Oksana Adams Dr. Phillip Wharton Dr. James Woodhall Source: http://www.nwpotatoresearch.com
QUESTIONS? Source: https://www.potatopro.com/news/2012/idaho-potato-commission-celebrates-75-year-anniversary