Symptoms:
Warm temperatures, in the 80°-90°F
range, and wet weather favor infection. The disease
first shows up as yellow flecks on the leaves, which
later turn dark brown. Individual spots are usually
irregular in shape and remain fairly small, surrounded
by a narrow yellow margin, but lacking a wide yellow
halo.
Solutions:
Plant disease-free seed, rotate crops, burn
infected plant tissues and clean contaminated equipment.
Avoid working with plants when they are wet,
as water transmits the bacteria. To prevent infection,
or reduce its spread, apply a copper soap fungicide at
7- to 10-day intervals. After heavy rain, or when the
amount of disease is increasing rapidly, apply every 7
days or more frequently at the highest recommended
rate. We recommend Soap-Shield Flowable Liquid Copper Fungicide.