Bacterial brown spot is a serious disease of snap beans particularly some yellow varieties. The disease has caused damage in a few snap bean fields in Ontario this past month. It is caused by bacteria (Pseudomonas syringae pv. syringae) that overwinter in previously infected snap bean debris or on contaminated seed. Once introduced into a field the bacterial pathogen can infect and multiply on emerging volunteer snap bean seedlings. The bacteria have also been found to survive for a period of time on the surface of plants without causing disease symptoms.
Symptoms of bacterial brown spot on snap beans first appear as small water soaked lesions usually observed on the underside of leaves. As the lesions mature, they turn brown and the dead tissue in the center may fall out giving the infected leaf a “shot hole” appearance (Figure 1). Sometimes a small light yellow or pale green border may surround the lesions. The bacteria can also infect pods resulting in brown water soaked spots making them unmarketable (Figure 2).
The Sweet Corn, Bean and Pea Integrated Pest Management Workshop will now also be available by webinar. If distance or time was preventing you from registering for the workshop, you can now get all the same great information, without the travel!
The workshop and webinar are planned for:
Tuesday, May 20th, 2014
1:00 pm to 3:30 pm
Room 102, Rudy Brown Rural Development Centre Ridgetown Campus, Ridgetown Ontario
Beans are susceptible to white mould infections during flowering and early pod-set. Small, circular, water-soaked lesions develop on the pods of infected flowers, or where fallen petals become caught in the lower canopy or leaf axils.
Infected tissues later develop a dense, cottony, white fungal growth. Leaves of severely infected plants will eventually turn yellow and fall off. Sclerotia (hard, black, irregular-shaped fruiting bodies) form in the branches, stems and pods of infected plants (Figure 1).
Increasing trap counts over the past several weeks indicate that the Western Bean Cutworm (WBCW) adults are nearing peak flight. With the early tassling of the field corn crop this year, vegetable crops may be under increased pressure of WBCW feeding. The appropriate approach to controlling WBCW will depend on the crop and the geographic area. Continue reading Western Bean Cutworm in Sweet Corn and Snap Beans→
The Pest Management Regulatory Agency (PMRA) recently announced the approval of a minor use label expansion for ASSAIL 70 WP insecticide (acetamiprid) for control of aphids on succulent shelled peas and beans, crop subgroup 6B in Canada. ASSAIL 70 WP (acetamiprid) was already labeled for management of a variety of insect pests on a range of crops in Canada.
Bean leaf beetles are a significant pest of snap beans in Ontario. The adults are 5 mm in length with four black spots on the wing covers. A small, black triangle is visible at the base of the head (Figure 1). The wing covers also have a black border. The colour of the bean leaf beetle varies from yellow to tan or red and the spots are not always present.
The Pest Management Regulatory Agency (PMRA) recently announced the approval of a minor use label expansion for PROWL H2O Herbicide (pendimethalin) for control of weeds on snap, lima and adzuki beans in Canada. Prowl H2O herbicide was already labeled for management of weeds on corn, soybeans and dry bulb onions in Canada.
These minor use submissions were sponsored in 2010 by the minor use office of OMAFRA in response to minor use priorities identified by producers and extension personnel in Canada. Additional data supporting these projects was provided by Dr. Darren Robinson, Dr. Peter Sikkema and D. Bilyea, U.ofG., Ridgetown and Todd Cowan, U.ofG., Huron.
Beans are susceptible to white mould infections during flowering and early pod-set. Small, circular, water-soaked lesions develop on the pods of infected flowers. Fallen petals on lower leaves or leaf axils are also common infection sites.
As the disease progresses, infected tissues develop a dense, cottony, white fungal growth. The leaves of severely infected plants will eventually turn yellow and fall off. Sclerotia (hard, black, irregular-shaped fruiting bodies) form in the stems and pods of infected plants.
White mould over-winters in infected crop residue and in the soil. The sclerotia will survive for up to five years in soil and crop residue.
The initial infection period requires moist soils and temperatures between 11 and 20º C (52-68º F.) A dense crop canopy often produces a cool, moist microclimate, ideal for white mould release. Plant surfaces must remain wet for 24-48 hours for infection to occur. Once established, the disease develops most rapidly between at temperatures between 20 and 25º C (68-77º F.) Fungal development essentially stops at temperatures over 30º C (86º F.)
If the weather conditions in the crop canopy are conducive to white mould infection, apply a white mould fungicide at 20% bloom followed by a second application 7-days later.
Information for commercial vegetable production in Ontario