Table 18: Scouting and Biological Control Guidelines for Vegetable Transplants

Pest How to Monitor Where to Look Biological Control Options
APHIDS Monitor weekly. Rely on plant inspection, not sticky cards. Look for small, 1/16" long aphids with two cornicles or "tailpipes" at the rear of the body. Identification to species is needed to determine which host specific aphid parasite to release when using biological controls. If uncertain, mixes of different species are available.  Underside of leaves and along stems on tips of new growth  of eggplant, pepper, tomatoes and many different leafy vegetables. Signs of aphid activity: shed white skins, shiny honeydew, presence of ants, curled new leaves, and distorted growth. Adalia bipunctata (predatory lady beetle); Aphelinus abdominalis (aphid parasite); Aphidius colemani (aphid parasite); Aphidius ervi (aphid parasite); Aphidius matricariae (aphid parasite); Aphidoletes aphidimyza (aphid midge, predator); Chrysoperla spp. (green lacewing, predator); Hippodamia convergens (predatory ladybeetle); Aphid Banker Plants (starter)
BACTERIAL LEAF SPOT On peppers, at first, chocolate-brown spots are less than 1/4" in diameter, and water-soaked in appearance. Severely spotted leaves appear scorched and defoliation may occur. Some strains also cause leaf spot on tomatoes.

Seed-borne disease.

More prevalent during moderately high temperatures, long periods of high humidity and leaf wetness.

BOTRYTIS BLIGHT Look for leaf blight and tan stem cankers. Botrytis blight produces characteristic gray fuzzy-appearing spores on the surface of infected tissues during humid conditions. In areas where plants are spaced close together and with leaf wetness and condensation dripping from plastic greenhouse coverings. Biological fungicides: Bacillus amyloliquefaciens; Bacillus subtilis; Clonostachys rosea, Reynoutria sachalinensis extract; Streptomyces sp.; Streptomyces lydicus; Swinglea glutinosa, Ulocadium oudemansii
BROAD MITES Look for symptoms of damage: leaf edges curling downward, twisted and distorted growth. With a 20x hand lens, or under a dissecting microscope, look on underside of leaves, especially on newest growth, for broad mites and their distinctive eggs. Near ornamental crops affected with broad mites. Near whiteflies (broad mites may hitch a ride on whiteflies). Peppers are especially susceptible. Amblyseius swirskii (predatory mites); Neoseiulus (Amblyseius) californicus (predatory mites); Neoseiulus (Amblyseius) cucumeris (predatory mites).
CATERPILLARS Inspect plants when adult moths are active, especially near cole crops. Look for caterpillars, their feeding damage and frass. Inspect plants near doors, openings, weedy areas and in greenhouses near vegetable fields. Bacillus thuringiensis subsp. kurstaki; Trichogramma spp. (egg parasite).
CYCLAMEN MITES Look for symptoms of damage: inward curling of leaves, puckering and crinkling. With a 20x hand lens or under a microscope, look within buds for mites and their eggs. Near ornamental crops affected with cyclamen mites. Amblyseius swirskii (predatory mites); Neoseiulus (Amblyseius) californicus (predatory mites); Neoseiulus (Amblyseius) cucumeris (predatory mites).
DAMPING-OFF (Pythium root and stem rot) Monitor seed flats of susceptible plants. Inspect weekly. Visually examine roots for cortex that sloughs off leaving central core. Inspect plants weekly for signs of disease: wilted, stunted, off-color plants with discolored root systems. Focus on areas where plants stay wet, or where there may be high populations of shore flies that may carry disease spores. High soluble salts/fertility increases susceptibility. Biological fungicides: Bacillus amyloliquefaciens; Bacillus subtilis; Clonostachys rosea, Reynoutria sachalinensis extract;  Streptomyces lydicus; Trichoderma aperellum & T. gamsii; Trichoderma harzianum; T. harzianum & T. virens.
DAMPING-OFF (Rhizoctonia root and crown rot) Monitor seed flats of susceptible plants including cole crops, peppers, and tomatoes. Look for small, water-soaked spots on stems or leaves before seedlings collapse. Seed flats near walkways or near dust and debris. Overcrowded seedling flats are more susceptible to damping-off. Biological fungicides: Bacillus amyloliquefaciens; Bacillus subtilis; Clonostachys rosea,  Reynoutria sachalinensis extract; Streptomyces lydicus; Trichoderma aperellum & T. gamsii; Trichoderma harzianum; Trichoderma harzianum and T. virens
FUNGUS GNATS Use sticky cards to monitor for adults. Place cards horizontally above soil surface. Potato chunks can be used to monitor for larvae. Check every two days. Favorable habitats include areas with standing pools of water, mud floors, spilled media, and weeds. Bacillus thuringiensis subsp. israelensis (pathogen); Dalotia coriaria (predatory beetles); Stratiolaelaps scimitus (predatory mites); Steinernema feltiae (nematodes)
LATE BLIGHT Look for sunken, water-soaked lesions on leaves and brown lesions on tomato stems or on potato bedding plants. Overwinters in potato cull piles or outdoors in field soil that is not completely frozen, so is not generally considered a problem for locally grown tomato transplants.  
(Spinach and beet leafminers)
Look for small, oblong, white eggs that are laid in neat clusters on the undersides of the leaves. Inside the mines look for one or several pale, white maggots. Scout undersides of leaves (beets, spinach, Swiss chard) for eggs and treat when they are first observed in order to target larvae as they hatch. The wasp parasitoid, Diglyphus isaea, which is most often used against Liriomyza leafminers (see Celery section) has also been reported to control leafminers in chard and  works best in warm weather.
POWDERY MILDEW Scout weekly. Look for faint, white fungal threads and spores on leaves. Scout near vents, or any location with a sharp change between day and night temperatures.  Biological fungicides: Bacillus amyloliquefaciens; Bacillus subtilisClonostachys rosea, Reynoutria sachalinensis extractStreptomyces lydicus, Swinglea glutinosa
SHORE FLIES Use yellow sticky cards to monitor for adults. Found near algae, their food source. Black frass  or insect droppings flecks the leaves.  Dalotia coriaria (predatory beetles); Steinernema carpocapsae (nematodes).
SLUGS Look for chewed holes in leaves and shiny patches of slime. Slugs hide under dense foliage, beneath pots and benches and in other protected locations. Chewed, irregular holes with smooth edges in leaves and slime that dries into silvery trails on foliage.  
SPIDER MITES (Two-spotted spider mites) Rely on plant inspection. Look for light flecking, speckling or discolored foliage, and webbing if high populations have developed. Look in hot, dry locations in greenhouse (i.e., near furnace) or near entrance ways. Amblyseius andersonii (predatory mites); Feltiella acarisuga (predatory midge); Neoseiulus (Amblyseius) californicus (predatory mites); Neoseiulus (Amblyseius) fallacis (predatory mites); Phytoseiulus persimilis (predatory mites).
THRIPS (Western flower thrips) Rely on sticky cards (placed just above crop canopy) and foliage inspection of key plants for early detection and to evaluate treatments.  Inspect plants by tapping tender new growth over a sheet of white paper. Watch for curled emerging leaves, distorted new growth on pepper. Look for white scarring and black frass (size of pin point) on tomato, cucumber and eggplant. Amblyseius swirskii (predatory mites); Dalotia coriaria (predatory beetles); Neoseiulus (Amblyseius) cucumeris (predatory mites);  Orius spp. (pirate bug, predator); Steinernema feltiae (nematodes); Stratiolaelaps scimitus (predatory mites); ornamental pepper banker plants "Purple Flash" and Lobularia for Orius.
TOBACCO MOSAIC VIRUS  Dark line patterns and distortion of leaves.  Spread by plant handling (no insect vector). TMV may be seen on tomato, pepper and eggplant, however, many vegetable varieties are resistant.   

Necrotic spot virus (INSV)

& Tomato spotted wilt virus (TSWV)

Symptoms will vary depending upon the host. On pepper, look for necrotic spots on the leaf. Ringspots may also develop. On tomato, leaves may develop small, dark brown spots. Thrips populations may be highest at front and rear of the greenhouse. Symptomless weeds may also be a source of virus. None. See thrips.
WHITEFLIES Rely on plant inspection to detect immature stages. Use sticky cards to monitor for adults. Egg-laying adults are found on the uppermost tender leaves of tomatoes, eggplant, and leafy greens. Immature stages are found on the undersides of leaves. Amblyseius swirskii (predatory mites); Chrysoperla spp. (Green lacewing, predator); Delphastus pusillus (catalinae) (predatory beetles);  Dicyplus hesperus (predatory bug), Encarsia formosa (Greenhouse whitefly parasite); Eretmocerus eremicus (Sweetpotato whitefly parasite).