Insects are an important obstacle to the healthy development of the watermelon industry, especially the tiny pests in the production of facilities, such as aphids, whiteflies, thrips and pest mites, among which the largest aphids are 2 mm long and the small ones are less than half a millimeters long. Such tiny pests have a wide range of hosts, the field is often staggered or overlapping, the reproduction speed is fast, the body size is small, the early monitoring and identification is relatively difficult, some pests are pest-like diseases, and the identification is inaccurate, which will lead to delayed control timing and affect the yield and quality of crops.
<h1 class="ql-align-justify" > first, pest occurrence hazard identification</h1>
1. Aphids
On the watermelon crop, aphids are mainly melon aphids, and the harm is common everywhere. Adult aphids and aphids cluster on the back of the leaves, young heads and stems, so that the melon leaves are deformed, curled, and a large amount of honeydew is excreted, inducing mold growth and reducing the photosynthesis of the plant. When the fruit is damaged, the value of the commodity is significantly reduced. In addition, aphids transmit a variety of melon virus diseases.
Aphids and their pests on melons
2. Whitefly
Whitefly pests include greenhouse whitefly and whitefly, with whitefly as the main pest everywhere. Whitefly use adults and nymphs to suck plant sap on the leaf back, causing physiological disorders, affecting plant photosynthesis, while secreting honeydew causes coal pollution and spreads plant virus diseases to cause greater harm, such as the Cucurbit chloroticyellows virus (CCYV) transmitted by whitefly.
Whitefly on melon leaves and their harmful appearance on the leaves
3. Thrips
The thrips produced by watermelon are dominated by palm thrips. Thrips use adults and nymphs to file the sap of young shoots, young leaves, flowers and young fruits of the host plant, making the leaves stiff, shrinking and thickening; the leaves leave silver-gray wound spots between the leaf veins, sometimes connected into one piece, and the black secretions of thrips often appear on the back of the leaves, and the victim plants are short, stunted, and easily confused with the symptoms of viral diseases. After the young melon is damaged, it hardens and browns, and in severe cases, it deforms or causes the melon to fall. At the same time as the thrips can also spread plant virus diseases, such as melon macular virus, which brings more indirect harm.
Thrips pest watermelon leaves front (left) and back (right)
4. Mites
The pests of watermelon production mainly include truncated leaf mites and diplodocal leaf mites, so as to become mites, young mites, and mites suck leaf sap and spit silk knots on the back of the leaves, which causes the leaves to lose green and die, and finally causes the whole plant to dry up and fall off, which can shorten the melon formation period of melon crops. It is worth noting that the yellow-green type of diplodocus is highly resistant and extremely difficult to chemically control in production.
Leaf mites cluster on the back of the leaf and its leaves are harmful
5. Spotted flycatchers
Spotted flies on melon crops mainly include American spotted diving flies and South American spotted flies, and adults and larvae can be pests. Female adults use an egg layer to puncture the epidermis of the leaf to form a white incisive puncture hole, female and male adults take leaf juice from the incision point, female worms lay eggs in the wound hole or cracks, the larvae hatch after moth to eat leaf flesh, with the increase of insect age The feeding area gradually increases, forming a snake-shaped white diving channel, reducing the photosynthesis of the leaf.
Spotted diving flies are pests on the leaves and larvae in the submersible passage
<h1 class="ql-align-justify" > second, micro pest control technology</h1>
The population of micro-pests is growing rapidly, and the prevention and control should follow the plant protection policy of "prevention first, comprehensive prevention", and adhere to the prevention and control measures of agricultural prevention, initial prevention, close monitoring and timely treatment.
1. Cultivate healthy grafted seedlings free of diseases and insects
Keep the nursery room clean before sowing watermelon seedlings; in the cultivation of the shed, cover 60 sieves with insect-proof nets for physical barrier; avoid mixed planting seedlings in the shed, and avoid raising seedlings in the shed room with growing plants to prevent pests from infecting the melon seedlings.
2. Colonization prevention treatment
The shed cultivation vents, doors and windows are covered with 60 sieve insect nets, and the residual leaves, weeds and autobiosis seedlings are cleaned up in time. Before seedling colonization, the endophoric insecticide 25% thiamethoxenide water dispersible granules 3000 times liquid or 10% bromocyanamide dispersible oil suspension 1000 times liquid can be used for burrowing disc spraying or dipping roots, or the root irrigation treatment (30~50 mL/plant) can be used after seedling colonization, which can prevent and suppress the population base of sucking mouthparter pests such as whiteflies, aphids, thrips, spotted flies, etc., and the prevention effect can reach more than one month.
Seedling pre-colonization pit disc spraying prevention (left) or post-colonization root irrigation prevention (right)
3. Yellow plate monitoring and booby traps
After the seedlings are colonized, the yellow armyworm plate is suspended, the lower edge of the yellow plate is slightly higher than the upper leaves of the plant, and adjusted with the growth of the plant, which can monitor the sporadic occurrence of pests such as aphids, spotted diving flies, whiteflies, thrips, etc., and can also play a role in trapping adult insects. The yellow plate may be removed when releasing parasitic wasps for biological control.
Yellow plates are hung in the field for monitoring and booby-trapping of adult insects
4. Prevention and control during the inset period
4.1 Biological control at low populations: Biological control can be used when the number of pest populations is low. For example, leaf mites are the dominant pest species in the shed, and the selection of the release of Chilean small plant mites can effectively control the pest mite population. In the cultivation of whitefly-based sheds, lice can release aphid wasps.
4.2 Timely chemical control: early application is the key to successful chemical control. In the timely time of low number of aphids, whitefly and other pests and the incidence rate of 5% to 10%, thiamethoxine, acetamiprid, ethyl spiroprid and other agents can be selected, and for aphids and whitefly that produce resistance, it can be selected to spray flufenacil, furazine amine, etc.; the thrips-based field blocks can choose ethyl polyfungalin, brombulin, methylpyridine salt, thiamethoxine and other agents; leaf aphids can choose biphenylhydrazine esters, acetazoles, etc.; spotted flies have high resistance to avermectin, and can choose to control flyamine. The above agents are administered according to the recommended doses, and attention is paid to the rotation of medications.
4.3 Smoke control in sheds: When the number of pest populations in sheds is large, smoke control methods can be used. You can choose 22% dichlorvos 250 g / 667 m2, or 20% iprovir tobacco 250 g / 667 m2, etc., at the end of the evening, the shed is closed, and the tobacco agent is divided into several parts to light the smoke to kill the adult insects. It should be noted that it must be used in strict accordance with the recommended dosage of tobacco, and the amount of drug cannot be increased arbitrarily.
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