Control Methods for Carrot Pests Such as Cabbage Caterpillars and Striped Bugs
Carrots are often attacked by pests during cultivation, mainly cabbage caterpillars, striped bugs, willow-carrot aphids, tobacco budworms, small leafroller moths, etc., which seriously affect the yield and quality of carrots and require timely control. The control methods for the main carrot pests are introduced below:
1. Carrot striped bug
It mainly damages carrots, fennel and other plants of the Apiaceae family, as well as radishes, Chinese cabbage, onions, scallions and other vegetables, and can also damage oak, elm, and Amur cork tree. Adults and nymphs cause damage, often resting on the leaves, flower buds and tender pods of host plants to suck sap, causing the plants to grow weakly; if seed-producing vegetables are damaged, the seed pods can become deformed and seed yields reduced.
Control methods:
Grasp the local peak period of egg hatching, and at the peak period of damage by adults and nymphs choose 2.5% deltamethrin EC 2000x solution, 1.8% abamectin EC 2000x solution, 90% trichlorfon crystal 1000-1500x solution, 50% phoxim EC 1000-1500x solution, or 50% malathion EC 1000-1500x solution, spraying once every 5-7 days during the peak occurrence period, for 2-3 consecutive treatments. Stop using the chemicals 7 days before harvest.
Image: Striped bug
2. Carrot willow-carrot aphid
Adults and nymphs mainly damage the tender shoots of Apiaceae plants, causing young leaves to curl, reducing yield and quality. Celery and fennel seedlings curl after being damaged. Carrot seedlings often turn yellow in patches after being damaged.
Control methods:
a. In early spring, apply pesticides on overwintering celery or nearby other vegetables where overwintering aphids are more numerous, to prevent winged aphids from migrating and spreading.
b. If there are many aphids on celery, spray 50% pirimicarb wettable powder 2000x solution, or 10% imidacloprid wettable powder 1500x solution, 50% phoxim EC 1000x solution, 50% malathion EC 1000x solution, 2.5% rotenone EC 600-800x solution, or 20% fenvalerate 2000-3000x solution. Stop using the chemicals 7 days before harvest
c. When aphids occur on celery in greenhouses, smoke agent No. 4 can be used, fumigating 350 g per 667 sq m, saving labor and being effective.
3. Carrot tobacco budworm
The larvae bore into and feed on buds, flowers and fruits, and also damage tender stems, leaves and shoots. After this pest feeds, it creates many notches and holes, and in severe cases only the leaf veins remain; fruits are bored into, causing rot and a large amount of fruit drop, which is the main cause of loss and reduced yield.
Control methods:
a. Field treatment after harvest. After harvest, clean the field in time and plow the land; before freezing, do a good job of winter irrigation of the vegetable field, or carry out deep plowing in winter and early spring, or rotate with non-solanaceous crops, so as to eliminate overwintering pupae of cotton bollworm and plant residues, reducing the base number of pest sources for the next year.
b. Use light trapping to kill pests. Installing insect-killing lamps and black light lamps in the field can trap and kill large numbers of adults.
c. For cotton bollworm control, spot-treat the first generation, vigorously treat the second and third generations, and pay attention to controlling the fourth generation. Also grasp the peak egg-laying period for pesticide application, carrying out a concentrated spraying within 3 days; the best effect is achieved when half of the eggs turn black. From the early peak period of cotton bollworm egg hatching to before the third-instar larvae, spray once every 7 days to eliminate the larvae before the third instar. For chemicals, choose highly effective, low-toxicity, low-residue pesticides; generally use 300-350 ml of Bacillus thuringiensis per mu, or spray 5% flufenoxuron EC 1000-1500x solution, or 10% imidacloprid wettable powder 2000x solution, or 25% fenvalerate. phoxim EC 1500x solution. The best application times are before 9:30 a.m. and after 4 p.m.
4. Carrot small leafroller moth
Generally, summer-sown carrots are damaged more severely. It occurs 5 generations a year, with the adult occurrence period from April to September. Eggs are laid singly and scattered on the ground. The occurrence amount varies greatly between years; generally, in years with high temperatures in July-August the occurrence amount is large, and it does not occur in cold regions.
Control methods:
Use 48% chlorpyrifos EC 500-800x solution for root drenching; 50% phoxim 1000x solution for root drenching; 40% dimethoate EC 1000x solution for root drenching; 90% trichlorfon crystal 1000x solution and other root drenching treatments.
5. Carrot cabbage caterpillar
The largest numbers and most severe damage occur from November to March of the following year (the peak planting period of cruciferous vegetables). Adults hide by day and come out at night, hiding in shaded places among field plants during the day, and when disturbed make short-distance flights among the plants. After mating, they mostly lay eggs near leaf veins, singly or in clusters of several, with an average of about 250 eggs per female. The egg stage is 3-11 days. After hatching, the larvae mine and feed on the leaf mesophyll; after the second instar they mostly feed on the underside of leaves, leaving the semi-transparent upper epidermis; after the third instar their food intake increases greatly, and they can bite the leaves into holes, and in severe cases only the leaf veins remain, causing the vegetables to lose their commercial value. The larvae are very active, and when disturbed they quickly twist backward or spin silk and drop down, but after a short pause they climb back up along the silk to the leaves and continue feeding. The larvae have 4 instars in total, with a developmental period of 12-27 days. Mature larvae mostly form cocoons and pupate near the leaf veins on the underside of leaves, and some pupate on fallen dead leaves. The pupal stage is 4-8 days. Adult lifespan is 11-28 days. Adults have strong phototaxis and need to feed on nectar to supplement nutrition.
Control methods:
a. Agricultural control: rational layout, trying as much as possible to avoid year-round continuous cropping of cruciferous vegetables, is a preventive measure to suppress major outbreaks of diamondback moth. Interplanting solanaceous crops has the effect of repelling insects and egg-laying. Timely removal of residual plants and leftover leaves after harvest can reduce the base number of pest sources.
b. Physical control: during the peak adult occurrence period, installing one black light lamp every 10 mu of vegetable field can trap and kill large numbers of diamondback moth adults.
c. Biological control: protecting and releasing Cotesia plutellae has a significant effect on reducing the natural population of diamondback moth. Apply Bacillus thuringiensis preparation B.t. emulsion or Qingchongjun No. 6 500-700x solution or granulosis virus; use the female sex pheromone “cis-11-hexadecenyl acetate” or “cis-11-hexadecenal” to trap and kill male moths; applying 20% diflubenzuron 500-1000x solution, or 5% chlorfluazuron, fenoxycarb, or flufenoxuron 2000x solution also has good control effects against resistant diamondback moth, and has a longer residual effect, and should be used as the main means of controlling diamondback moth.
d. Chemical control: 5% fipronil suspension concentrate or 10% chlorfenapyr suspension concentrate 2000-3000x solution; 20% bromfenvalerate EC 3000-4000x solution both have good control effects.