WSU CAHNRS and WSU Extension


Search plant problems by plant name

? Help on search

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  R  S  T  V  W  Y 

Plant NameTypeDescription 
Black rotBroccoli, Cole cropsDiseaseBlack rot is a bacterial disease affecting most cultivated and weedy plants in the mustard family. Cabbage and cauliflower are the primary cultivated hosts in Washington. The bacteria enter via wounds or at the leaf margins. Infected leaves turn yellow, with the chlorosis spreading from the infection site toward the base of the leaf and causing a V-shaped area along the main vein. Veins in the affected area turn black and show against the light as a black network. Affected leaves may drop. The disease moves into the tissues of the stem, causing the water-conducting tissues to turn black. The infection becomes systemic after entering the stem and can then cause symptoms on any part of the plant. The bacteria overwinter on plant debris and weeds and in infected seed. They require water to spread.
ClubrootBroccoli, Cole cropsDiseaseClubroot is a disease that affects plants in the mustard family. It is caused by a soil-borne fungus-like organism. Affected plants develop abnormally large roots which may become swollen and club-shaped. Affected seedlings often die, while plants that are infected later usually develop severely distorted roots. The swellings may be on taproots, fine roots, or even on underground stems. Broccoli, cabbage, and cauliflower typically form spindle-shaped clubs on their fibrous roots. Fleshy-rooted host plants such as radish, rutabaga, and turnip develop more spherical clubs on the tap root or secondary roots. Unstressed plants with minor infections may show no aboveground symptoms. However, severe infections limit the ability of plants to take up water and nutrients, and may result in stunted growth, yellowing leaves, and daytime wilting during hot weather. Premature bolting (flowering and setting seed) may also occur. Clubroot is more severe on plants in cool, wet, acidic soils. The pathogen produces motile spores that can swim in wet soils. These spores can be moved by irrigation water, contaminated soils, infected plants and plant material, and by soil-contaminated tools and footwear. The pathogen is reported to survive up to 18 years in contaminated soil. In addition to the mustard family, plants in the rose, poppy, and grass families may be affected.
Downy mildewBroccoli, Cole cropsDiseaseDowny mildew is a fungal disease typically found on leaves of broccoli, cabbage, and other plants in the mustard family including weeds. Leaves first show pale green to yellowish spots on the upper surface which turn more yellow as they enlarge. The underside of infected areas later develop grayish to white fungal growth. Stems of broccoli may also be affected, showing spots on the outside and brown to purple streaks internally. Heads of broccoli and cauliflower may be dark brown or black inside, while cabbage heads may show small, sunken, black spots. Downy mildew development is favored by cool, humid weather.
OedemaBroccoli, Cole cropsDiseaseOedema is a physiological problem. Symptoms are usually seen on the lower side of leaves, but may occur on any part of the plant. Watery blisters or gall-like structures form, and later turn dark brown or yellow. They may become somewhat corky in appearance. The later stages may resemble rust diseases. Oedema often occurs when soil temperatures are higher than air temperatures and soil moisture and relative humidity are high. Mechanical injury to leaves, such as that caused by insect feeding, windblown soil, or chemical injury, may also result in oedema.
AphidsBroccoli, Cole cropsInsectAphids are small, pear-shaped, soft-bodied insects. They may range in color from yellowish to a waxy gray-green. Aphids typically feed on the underside of leaves, in buds, or in heads of broccoli or cauliflower. Aphid feeding can cause foliage to yellow. Wilting or stunting of plants may occur if infestations are severe. Aphid feeding produces honeydew, a sweet, sticky material which may attract ants or become covered with a dark growth of sooty mold. Some species can overwinter as eggs on plant debris.
Cabbage maggotBroccoli, Cole cropsInsectThe cabbage maggot is the larva of a gray fly that is about 3/16" long. Females lay eggs near the base of plants such as cabbage, broccoli, cauliflower, radish, and turnip. The white larvae make tunnels and grooves in the roots and underground portions of stems. Soft rots may infect these areas, causing further damage. The leaves of affected plants are often yellow and stunted. Severe damage can result in wilting and death of plants. Younger plants are more severely damaged. Mature larvae are up to 3/8" in length. They pupate in the soil, with up to three generations occurring in a season. The last generation of the season overwinters in the soil, hatching into adults in early spring.
Flea beetlesBroccoli, Cole cropsInsectFlea beetles are small, brown to metallic black beetles with a habit of jumping like fleas when disturbed. They feed on many plants including beets, kale, collards, radish, and many weeds, particularly those in the mustard family. Small round holes are eaten in the leaves, usually early in the season. The larvae typically feed on underground portions of the host plants. Damage can be very severe on seedling plants.
Imported cabbagewormBroccoli, Cole cropsInsectThe imported cabbage worm is the larval stage of the cabbage butterfly. The adult butterfly has white wings, with black tips and spots on the forewings. Wingspan is about 1-1/2". Eggs are laid in the spring on the leaves of host plants, which include cole crops such as broccoli and cabbage, as well as radish, turnip, and nasturtiums. The caterpillars are green with faint yellow stripes along the back and sides. They feed on the leaves, chewing irregular holes in the leaf tissues. Mature caterpillars are about 1" long and may also feed in the center of cabbage heads. Black pellets of frass (excrement) are often present on the leaves. The caterpillar pupates in a pale green chrysalis which may be attached to any convenient object in the garden. Three to five generations may occur in a single season.
LoopersBroccoli, Cole cropsInsectLoopers are typically green caterpillars up to about 1-1/2" long. They may have pale or dark stripes along the body. They are distinguished by their characteristic looping or measuring-worm movement. Loopers feed on leaves of many plants, chewing holes in the leaves or feeding along leaf margins. The adult moth of the cabbage looper, one common species, is gray-brown and has a silvery spot on each forewing. Cocoons of this species can often be found attached by one side on leaves. The alfalfa looper moth is mottled brown with silver markings. Both species have a wingspan of about 1-1/2". Eggs are laid on leaves of host plants.
ThripsBroccoli, Cole cropsInsectThrips are tiny (1/20" or less), elongate, yellowish to dark insects. Thrips feeding can result in whitish stippling or streaking of leaves. Buds may be damaged, resulting in misshapen plant parts. Thrips are an occasional problem in cabbage.