SYMPTOMS
Leaves develop small, angular, light brown spots. The spots are angular because their growth is limited by leaf veins. Spots may enlarge to nearly ½ inch (13 mm) in diameter and coalesce into blotches.
DIAGNOSIS
Stemphylium leaf spot (Stemphylium botryosum, S. herbarum)
SOLUTIONS
• Sanitize
• Weed
• Mulch
• Use beneficial fungi
• Use beneficial bacteria
• Use baking soda spray
• Use copper
• Plant polycultures
• Choose genetically resistant plants
• Rotate crops
• Create healthy soil
• Decrease nitrogen
• Keep foliage dry
SYMPTOMS
Leaves develop yellow spots that vary in size and are angular in shape (because their growth is limited by leaf veins). Leaf undersides develop grayish velvety fuzz. Spots enlarge, and leaves become twisted and distorted. Leaves turn brown and drop off plant.
DIAGNOSIS
downy mildew (Pseudoperonospora cannabina, P. humuli)
SOLUTIONS
• Sanitize
• Weed
• Mulch
• Filter the air
• Move the air
• Use beneficial bacteria
• Use baking soda spray
• Use copper
• Plant polycultures
• Choose genetically resistant plants
• Rotate crops
• Create healthy soil
• Decrease nitrogen
• Keep foliage dry
SYMPTOMS
Small, wet-looking, angular spots (confined by leaf veins) on leaves grow larger, turn yellow and then brown or gray. Dead tissue inside spots may break apart, leaving ragged holes. Plants become stunted and deformed and may die. These diseases are spread by splashing water, wind-driven rain, insects, and people.
DIAGNOSIS
bacterial leaf spot: bacterial blight (Pseudomonas syringae pv. cannabina), Xanthomonas blight (Xanthomonas campestris pv. cannabis), wildfire (Pseudomonas syringae pv. tabaci), Wisconsin leaf spot (Pseudomonas syringae pv. mellea)
SOLUTIONS
• Sanitize
• Weed
• Mulch
• Plant polycultures
• Choose genetically resistant plants
• Rotate crops
• Create healthy soil
• Keep foliage dry
SYMPTOMS
Earliest symptoms are small, dull green, angular leaf spots. Plant soon wilts and collapses. Leaves and stems turn brown and die. Cut stem in half to look for highly viscous fluid oozing from stem. This pathogen is transmitted by cucumber beetles and is found in cucumbers, squash, and pumpkins.
DIAGNOSIS
bacterial wilt (Erwinia tracheiphila)
SOLUTIONS
• Sanitize
• Weed
• Mulch
• Use row covers
• Plant polycultures
• Choose genetically resistant plants
• Do not plant near cucumber family
• Rotate crops
• Create healthy soil
• Keep foliage dry