||Yellow/brown/purple/black spots on leaves; sunken, dark spots on stems and fruit; spots may develop a salmon-pink, gelatinous mass; eventually, plants rot
||Destroy infected plants; choose resistent varieties; provide good drainage; avoid overhead watering; apply compost for nutrition; use mulch; practice crop rotation. Find images and more information about anthracnose here.
||Misshapen/yellow leaves; distorted flowers/fruit; sticky “honeydew” (excrement produced by aphids); sooty, black mold that forms on honeydew; large presence of ants on plants
||Grow companion plants to either attract aphids away (nasturtiums) or repel them outright (basil, rosemary, strong-scented plants); knock aphids off plants with water spray, apply insecticidal soap; put banana or orange peel around plants; wipe leaves with a 1-2% solution of liquid dish soap and water every 2-3 days for 2 weeks; add native plants to attract aphid predators. Find images and more information about aphids here.
||Caused by lack of sufficient calcium uptake.
Symptoms: dark, water-soaked spots on blossom end of fruit (the side opposite the stem) may enlarge and become sunken, leathery, rotted
|Remove affected fruit; plant at proper soil temperature; water deeply and evenly; use mulch; maintain proper soil pH (6.5) and nutrient levels; avoid excessive nitrogen; provide good drainage; avoid damaging roots. Find more images and information about blossom-end rot here.
|Colorado Potato Beetles
||Yellow-orange eggs laid in clusters on leaf undersides; larvae and adults chew holes in foliage
||Remove eggs/larvae/beetles by hand; use straw mulch; weed around plants; use row covers; destroy plant matter at end of season; practice crop rotation
||Numerous tiny holes in leaves (as if they had been hit by a tiny shotgun)
||Use row covers to physically block flea beetles; mulch heavily; add native plants to attract beneficial insect predators. Find more information and images of flea beetles here.
|Mosaic Virus (Cucumber)
||Symptoms vary, but may include: stunting; mottled green/yellow/white pattern or ringed spots on leaves/fruit; distorted leaf growth; warts on fruit
||Often spread by aphids. Destroy infected plants; choose resistant varieties and certified virus-free seed; use row covers; disinfect gardening tools after each use; keep garden weed-free; use mulch. Find images and more information about mosaic viruses here.
||Roots become “knotted” or galled; plants stunted/yellow/wilted
||Destroy affected plant matter (especially roots); choose resistant varieties; expose soil to sun (solarize); add aged manure/compost; disinfect gardening tools between uses; till soil in autumn; practice crop rotation
||Chewed leaves (initially toward top of plant); rapid defoliation; black/green excrement; gouged fruit
||Check undersides of leaves for hornworms, remove by hand and dispose of hornworms. (If you encounter hornworms that have white, ricelike cocoons on their backs, relocate them instead; the cocoons belong to beneficial parasitic wasps.) Till soil in autumn and spring; companion plant with dill/basil/marigolds to attract (and trap) or repel hornworms; spray plants with Bt (Bacillus thuringiensis). Find images and more information about hornworms here.