Root Crops in the Home Garden

This article covers insect identification and control of some common pests of root crops.
Root Crops in the Home Garden - Articles
Root Crops in the Home Garden

Flea Beetles

The most serious injury is caused to young plants early in the growing season. Small holes are eaten in the leaves, or the leaves are skeletonized by small, round, shiny beetles about 1/16 inch long. These beetles jump readily when approached. Injury gives plants a ragged and bleached appearance and growth is slowed.

Control

Clean cultivation and weed control around the garden are important since the beetles feed on many weeds. Suspending a floating row cover above the crop immediately after planting can protect plants from damage. Plants with vigorous growth can withstand fairly high levels of feeding without reducing total plant health and lightly infested leaves can be discarded. When injury exceeds your tolerance, spray with an insecticide labeled to control flea beetle on vegetables. Consult the most recent Commercial Vegetable Production Guide for specific control measures. Follow directions on the labels according to plant type when applying insecticides.

Green Peach Aphids

Aphids are small, soft-bodied, greenish, sucking insects. They feed by inserting their needle-like mouthparts into plants and sucking out the sap. They are often recognized in large colonies that form on the leaves and stems. They overwinter as eggs on peach trees. Eggs begin to hatch as peaches bloom. During early spring they stay on peach trees for several generations. Most aphids are wingless but when conditions become crowded or when food becomes depleted, some aphids develop wings and move to other garden plants and weeds. They produce many generations on the summer plants on which they feed.

Control

Clean cultivation and weed control around the garden are important since aphids feed on many weeds. When aphids first appear, spray with insecticidal soap or an insecticide labeled to control aphid on vegetable crops. Aphid populations are heavily influenced by temperature, rainfall, number of natural enemies present and pesticide applications. Aphid outbreaks tend to be most frequent in hot, dry weather, while heavy rains (or directed sprays of water) will often reduce the aphid population to acceptable numbers. Consult the most recent Commercial Vegetable Production Guide for specific control measures. Follow directions on the labels according to plant type when applying insecticides.

Leafminers

Plants are often disfigured and damaged by several species of small flies that live in the maggot stage in the leaf tissue, between the upper and lower surface. Feeding causes large white blotches and winding trails through the interior of the leaves, which are rendered unattractive and unfit for human consumption.

Control

Row covers can protect plants from leafminer damage. Individual leaves can also be removed and destroyed as feeding damage is noticed. Otherwise, when mines first appear, spray with an insecticide labeled to control leaf miner in vegetables. Note: insecticides cannot control maggots already inside leaves at the time of application. Consult the most recent Commercial Vegetable Production Guide (available at your County Extension Office) for specific control measures. Follow directions on the labels according to plant type when applying insecticides.

Carrot Rust Fly

The maggot of the rust fly is a pest of both carrots and parsnips.

Control

Since rust fly is not a problem every year, it may not prove practical to attempt control. Row covers can be used to protect the crop. When rust fly injury is first noticed, spray with an insecticide labeled to control rust fly in vegetables. Consult the most recent Commercial Vegetable Production Guide for specific control measures. Follow directions on the labels according to plant type when applying insecticides.

Cabbage Maggot

Radish, turnip, and rutabaga are favorite hosts for the cabbage maggot. There are four and sometimes five broods (generations) of the maggot per season. The first brood emerges in April when the Yellow Rocket weed is in bloom.

Control

Do not plant in the same location that plants in the crucifer family (broccoli, brussels sprouts, cabbage, cauliflower, kale) were grown the previous year. Avoid planting into fields that have recently decaying organic matter such as immediately following the plowing under of animal manure or a cover crop. Maintain plant vigor. Remove and destroy infested plants. Crops can be protected by using a floating row cover held at least 6" from the plants to prevent the adult flies from laying eggs near the bases of the plants.Cool, wet springs promote conditions that contribute to high populations of cabbage maggot. Fields of cruciferous vegetables should be scouted and closely evaluated for cabbage maggot, especially during years with favorable conditions. The first summer generation of the cabbage maggot is the most damaging to plant health. Young plants are not able to withstand much root feeding from the cabbage maggot before wilting and death occur, especially if temperatures are low. Plants growing in warmer conditions can grow past low to moderate numbers of cabbage maggots. Consult the most recent Commercial Vegetable Production Guide for specific control measures. Follow directions on the labels according to plant type when applying insecticides.

Warning

Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds.

Authored by: Shelby Fleischer

February 2000