Chocolate Spot
Severe attack of chocolate spot, close up of leaf symptoms & severe disease pressure
Pathogen
Fungus
Hosts
Field and broad beans
Symptoms
Red / chocolate brown leaf and pod spots, streaky stem lesions and stained seed. These symptoms coalesce during the aggressive phase of the disease and cause flower or pod rotting, defoliation and early senescence.
Development
Plants can be infected by old bean crop debris, volunteer beans, seed, soil-borne sclerotia or air-borne spores.
Favourable Factors
Wet, humid weather, thick winter crops, poor drainage and frost damage.
Importance
The most widespread and serious disease of field beans, particularly in winter crops. Can lead to yield reductions of up to 25 % and under severe disease pressure can cause complete defoliation of the crop and possibly even complete crop failure.
Control
There are no resistant varieties
Sow winter crops after mid-October to avoid early infections
Remove crop debris after harvest
Apply foliar fungicides at the first signs of disease from the early flower stage and a follow-up spray may be needed 3-4 weeks later if cool, wet conditions persist.
