Colletotrichum: causal fungus of anthracnose diseases• Citrus
• Pepper
• Cucurbits
• Onion
• Spinach
• Blueberry
• Eggplant
• Tomato
• Potato
• Cabbage
• Beans
• Banana
On runnerAfter incubation in moist chamberPhoto by K. Ivors
Wet spore masses need water splashing to spread
Or physical movement on people and equipment
Not windborne
History of anthracnose in Calif.
• Last major outbreak occurred in 2001-02
• Current outbreak in 2015-16• Mainly in Oxnard and Santa Maria
• Especially summer plantings in 2015
(Jan 1 – present)149 plant samples processed
25% Colletotrichum acutatum
10% Fusarium oxysporum9% Macrophomina phaseolina4% Verticillium dahliae4% Phytophthora spp.3% Cylindrocarpon destructans2% Colletotrichum gloeosporioides
43% Abiotic
2016 Summer planting: anthracnose only detected on non-dipped transplants (organic field)
2016 Disease Diagnostics
Dip Treatmentsfor control of
Anthracnose Crown RotHaack, S., Adaskaveg, J., Forster, H. (UC Riverside)
Gubler, D., (UC Davis)
Ivors, K. and Holmes, G. (Cal Poly SLO)
Treatments
• Control (no water)
• Control (water rinse)
• Actinovate, 24 oz
• Azoxystrobin, 8 fl oz
• Bravo, 24 fl oz
• Switch, 8 oz
• Syngenta-1, 5 fl oz
• Syngenta-2, 7 fl oz
• EXP-13, 13.3 oz
• Exp-13, 26.6 oz
• Syngenta-1+EXP-13, 5 fl oz + 13.3 oz
= Zivion (ai = natamycin)
All treatments evaluated under these conditions:• Two types of pathogen
• Azoxystrobin-resistant isolates
• Azoxystrobin-sensitive isolates
• Two types of infection• Artificially inoculated
• Naturally inoculated
• Two cultivars• Portola (more susceptible)
• Fronteras (less susceptible?)
4-min dip w/ agitation
Drip drain for 5-10 min
Stored at 37F overnight
(Treated in afternoon; planted next morning)
Conclusions
• Artificial inoculation resulted in very high levels of disease and is an effective means of evaluating treatments
• Natural infection also resulted in high levels of disease• Treatments produced significant effects and yield
reductions
Conclusions
• Fronteras ~2X more resistant to anthracnose than Portola
• Actinovate: no efficacy measured under these conditions
• Azoxystrobin: highly effective IF Colletotrichum is sensitive• No efficacy IF Colletotrichum is resistant
• Switch: highly effective• No phytotoxicity detected under these conditions
• New compounds (EXP-13 and Syngenta-2) with high efficacy• Potential for registration of EXP-13 biofungicide (Zivion)