During the period of flower bud through bloom, start sweep net sampling for lygus bugs twice weekly. Also look at overall stand quality and use the table below and the photo identification page to help identify other pests and damage.
| What the problem looks like: | Check for: | Possible cause(s): |
|---|---|---|
| Collapsed, wilting, stunted, or dying plants | Charcoal-like dust appearance on stem and root surface near the soil line | Charcoal rot |
| Water-soaked lesions on stem at, below, or just above the soil line | Pythium diseases ("wilt") on established plants | |
| Yellowing leaves; center of the root and xylem tissue in above ground stem have reddish-brown discoloration that can be seen when cut open | Fusarium wilt/yellows (blackeyes) | |
| Brick-red lesions on portion of stems below ground; tap roots eventually turn brown | Root rot (Fusarium spp.) | |
| Root galling; brown-black root lesions | Nematodes | |
| Yellowing leaves | Leaves yellow or dry and slightly curled; honey-dew or sooty mold sometimes present | Whitefly, aphids |
| Striking yellow mottle | Alfalfa mosaic | |
| Soil saturation | Too much water leading to iron deficiency | |
| Mottled, distorted leaves | Striking yellow mottle | Alfalfa mosaic |
| Green-yellow and dark green mosaic pattern on leaves; discoloration usually accompanied by puckering, blistering, downward curling | Bean common mosaic | |
| Bright, yellow to green mosaic or mottling; leaves distorted, cupped downward, and wrinkled | Bean yellow mosaic | |
| Damaged flower buds and blossoms | Lack of flowers; plant bugs present (if no plant bugs, could be due to high temperatures) | Lygus bugs, stink bugs |
| Leaves with holes; skeletonized leaves | Presence of mottled, olive-green to almost black caterpillars; or, black caterpillars with prominent yellowish stripe and several bright stripes on each side | Armyworms |
| Presence of green caterpillars that arch backs when crawling | Loopers | |
| Presence of yellow, brownish to black caterpillars with yellow lines, covered with reddish or black hairs. | Saltmarsh caterpillar | |
| Presence of greenish-yellow beetles with black spots or stripes | Cucumber beetles | |
| Leaves with mines | Slender, winding trails or large, whitish blotches | Leafminers |
| Curled leaves | Sticky, shiny leaves; black sooty mold; presence of aphids or whiteflies | Whitefly, aphids |
| Leaves with spots | Irregularly shaped spots bordered by a lemon-yellow ring; dead brown tissue in center of larger spots | Common bacterial blight |
| Necrotic spots on infected leaves; yellow dots | Alfalfa mosaic | |
| Leaves with stippling | Very fine white or yellow stippling; fine webbing on leaf undersurface | Spider mites |
| White stippling on upper surface of leaf; tiny, dark, varnish-like spots and small, white cast skins on lower surface of leaf | Leafhoppers |