Like other cole crops such as Brussels sprouts, cabbage and cauliflower, broccoli has its share of pests. Bugs come out in force to feed on this cool-season vegetable despite preferable growing temperatures of only 60 to 65 degrees Fahrenheit. The first step toward defeating these pesky foes is to identify them.
Worms and Caterpillars
The smooth-skinned armyworm feeds in groups, skeletonizing leaves and eating the crowns of broccoli seedlings. The cabbage looper, the larva of a grayish brown moth, prefers to feed alone, consuming the underside of leaves. Cabbage webworms, another moth larva, initially feed on both sides of whatever leaves they hatch on. As they mature, they make a protective silk web on young broccoli plants and then tunnel into the buds, eventually killing them.
The bright yellow, semi-transparent eggs of the cross-striped cabbageworm can be found in groups of 20 to 30 on the underside of plants. When they hatch, the cabbageworms eat the heads and buds of broccoli, leaving them riddled with holes. Light green with black hairs covering their bodies, diamondback moth caterpillars feed on all parts of broccoli plants. Instead of eating completely through leaves, they leave "windows" of thin foliage.
The larva of a yellowish-white butterfly, an imported cabbageworm is velvety green with a narrow orange stripe down the middle of its back. It isn't a picky eater, chewing through broccoli plants indiscriminately. Wireworms prefer to feed on roots or shoots while cutworms like to bite off seedling stems just below the soil level, and microscopic nematodes live and feed in plant roots.
A plant infested with cabbage maggots will look off-color and stunted, sometimes wilting suddenly during the hottest part of the day and dying. The yellowish leafminer maggots feed underneath leaves and leave a twisted trail of destruction behind while seedcorn maggots kill germinating seeds and small seedlings.
The cabbage aphid and turnip aphids cover broccoli plants in a dense cluster of whitish-green lice-like bugs. Both types of aphids suck sap from broccoli leaves, which are left curled and crinkled.
The harlequin bug sucks sap from the leaves of broccoli plants, leaving the plant to wilt and eventually die. Although less common, crickets come out at night and kill entire crops in a few days. The darkling beetle is another nocturnal nibbler, feeding on seedlings as well as the foliage of more mature plants.
Thrips scar broccoli plants by puncturing them and sucking out the cell contents while whiteflies also suck out a plant's sap, leaving behind a sticky honeydew trail.
- University of California Statewide Integrated Pest Management Program: Pests in Gardens and Landscapes: Time to Plant
- Clemson Cooperative Extension; Cabbage, Broccoli and Other Cole Crop Insect Pests; Randall P. Griffin; February 1999
- University of California Integrated Pest Management Program: Pests in Gardens and Landscape: Broccoli
- Photo Credit PhotoObjects.net/PhotoObjects.net/Getty Images
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