Strawberries have entered the flowering stage, and the main pests on strawberries-aphids, thrips, spider mites, etc. are also starting to attack. Because spider mites, thrips, and aphids are small pests, they are highly concealed and difficult to detect in the early stage. However, they reproduce quickly and can easily cause disasters and cause large economic losses. Therefore, it is necessary to strengthen the pest situation survey to achieve early detection and early prevention and control.
Symptoms of harm
1. Aphids
The main aphids that damage strawberries are cotton aphids and green peach aphids. Adults and nymphs cluster on the underside of strawberry leaves, core leaves, and petioles, sucking strawberry juice and secreting honeydew. After the growth points and core leaves are damaged, the leaves curl and twist, affecting the normal growth of the plant.
2. Thrips
After the strawberry leaves are damaged, the damaged leaves fade and leave tooth marks. The leaves initially show white spots and then become connected into sheets. When the damage is severe, the leaves become smaller, shrink, or even yellow, dry, and wither, affecting photosynthesis; during the flowering period, the leaves are damaged. Damage may cause stamen distortion, flower sterility, petal discoloration, etc. Adult insects can also damage fruits and affect the economic value of fruits. In addition, thrips can also spread a variety of viruses and cause damage to strawberry production.
3. Starscream
The main species of spider mite that damages strawberries is the two-spotted spider mite. The female adult mite is dark red with black spots on both sides of the body and is oval in shape. Overwintering eggs are red, while non-overwintering eggs are less pale yellow. Young mites of the overwintering generation are red, while young mites of the non-overwintering generation are yellow. The nymphae of the overwintering generation are red, and the nymphae of the non-overwintering generation are yellow with black spots on both sides of the body. Adult, young and nymphal mites suck sap on the underside of leaves and build webs. At the initial stage, sporadic chlorosis spots appear on the leaves, and in severe cases, white dots are scattered all over. In severe cases, the leaves scorch and fall off, causing premature plant aging.
Occurrence rules
1. Aphids
Aphids mostly move around young leaves, petioles, and leaf undersides to suck sap and secrete honeydew to contaminate the leaves. At the same time, aphids spread viruses and degrade seedlings.
2. Thrips
Warm, dry weather favors this. It occurs every year in the solar greenhouse and breeds and overwinters there, usually 15-20 generations/year; it occurs in the greenhouse in spring and autumn until harvest. Nymphs and adults often lurk in the center of flowers and overlapping petals, and are highly concealed. It is difficult for general insecticides to directly contact and kill the insects.
3. Starscream
Young mites and early stage nymphs are not very active, while late stage nymphs are active and gluttonous and have the habit of climbing upwards. It affects the lower leaves first and then spreads upward. High temperature and drought are most conducive to the occurrence of spider mites, and long-term high humidity conditions make it difficult to survive.
Prevention and Control Technology
1. Aphids
(1) Agricultural measures: promptly remove old and diseased strawberry leaves and clear weeds around the greenhouse.
(2) Physical prevention and control: Set up insect-proof nets in ventilation positions; set up yellow boards to trap and kill them in the greenhouse. They will be used from the planting period. Each greenhouse uses 10-20 pieces, and the hanging height is slightly higher than the strawberry plants by 10-20 cm. Trap winged aphids and replace them regularly.
(3) Biological control: In the early stages of aphid occurrence, ladybugs are released in the field, and 100 calories per acre (20 eggs per card) are released to kill aphids. Pay attention to protecting natural enemies such as lacewings, hoverflies, and aphid braconid wasps.
(4) Chemical control: You can use 25% thiamethoxam water-dispersible granules 3000-5000 times as liquid, 3% acetamiprid EC 1500 times as liquid, and 1.8% abamectin EC 1000-1500 times as liquid. Pay attention to rotation of medication. Pay attention to the safety interval of pesticides to avoid the development of pesticide resistance and phytotoxicity. (Note: For spray control, avoid the strawberry flowering period, and move bees out of the shed when applying pesticides.)
2. Thrips
(1) Agricultural prevention and control: Clear weeds in vegetable fields and surrounding areas to reduce the population base of overwintering insects. It is more severe during drought, so the damage can be reduced by ensuring that plants are well irrigated.
(2) Physical control: Blue or yellow insect traps are used to trap thrips, which is more effective. Hang 20-30 pieces per acre, and the lower edge of the color plate should be 15-20cm from the top of the plant, and increase as the crop grows.
(3) Biological control: The number of thrips can be effectively controlled by using natural enemies of predatory mites. If thrips are found in the greenhouse, timely release of 20,000 Amblysei mites or new cucumber mites/acre, once a month, can effectively control the damage. Pesticides are not allowed to be used 7 days before and during the release period.
(4) Chemical control: When the insect load is low, use 2% emamectin EC 20-30 g/mu and 1.8% abamectin EC 60 ml/mu. When the insect load is severe, use 6% spinosad 20 ml/acre for foliar spraying. When using pesticides, firstly, we must pay attention to the alternate use of different pesticides to weaken their resistance. Secondly, we must pay attention to spraying pesticides not only on the plants but also on the ground when spraying, because some mature larvae pupate in the soil. (Amamectin and abamectin are toxic to bees. When spraying for control, avoid the strawberry flowering period, and move bees out of the shed when applying pesticides; spinosad is not toxic to bees.)
3. Starscream
(1) Agricultural prevention and control: clear weeds in the field and eliminate the source of overwintering insects; promptly knock off the lower old leaf insect leaves and take them out of the field for centralized destruction.
(2) Biological control: Use natural enemies to control the population of red spider mites in the early stages of occurrence, and release Amblyseidia barbari in the field, with 50-150 individuals/square meter, or Phytoseiid mites with 3-6 individuals/square meter.
(3) Chemical prevention and control: For initial use, 43% diphenazine suspension 2000-3000 times and 1.8% abamectin 2000-3000 times can be used for spraying. Control once every 7 days. The effect of alternate use of chemicals will be better. good. (Diphenyl hydrazine and abamectin are toxic to bees. When spraying for control, avoid the strawberry flowering period, and move bees out of the shed when applying pesticides.)
Post time: Dec-18-2023
