Watermelon Main Disease and Insect Pest Control Technology

Abstract: Watermelon is a creeping plant belonging to the Cucurbitaceae family. It is suitable for growing in a warm and sunny environment and is not resistant to cold. It has a sweet taste, contains a lot of water, and has a variety of nutrients. It can be eaten in summer to relieve the heat. Based on this, the global watermelon planting has been greatly dev eloped. Through the use of large-scale planting methods, the production of watermelon around the world has remained high. However, due to various reasons, there are more and more watermelon-related diseases and insect pests, which has hindered the development of watermelon industry in many areas. The main watermelon diseases and insect pests and their control techniques are described below by taking the watermelon cultivated in the open field as an example.

1. Control technology of main diseases and insect pests of watermelon cultivated in open field

The main pest control techniques for watermelon cultivated in open field are divided into non-chemical control techniques and chemical control techniques. Among them, non-chemical control technologies are further subdivided into physical control and biological control. Chemical control technology is subdivided into chemical control for different watermelon disease symptoms and control for diseases and insect populations.

2. Non-chemical control technology of watermelon diseases and insect pests

2.1 Physical control

Physical control is mainly used to prevent pests that occur during the growth of watermelon. Unlike chemical control, physical control costs very low and does not cause pesticide residues. The phototaxis of some insects to different colors of light is used to eliminate pests as a control principle. Basically, It will not cause harm and will not affect the growth of watermelon. For example, using the yellowing phototaxis of aphids, evenly apply yellow paint on wood or cardboard, and apply a layer of grease on the surface to eliminate aphids.

2.2 Biological control

Biological control includes natural enemy control and biological pesticide control. According to the characteristics of the ecological chain and energy flow in nature, the natural enemies of pests are selected to prey on pests, so as to control the number of harmful organisms. In the watermelon planting industry, the natural enemies of aphids are Trichogramma and lady beetles, so the introduction of Trichogramma and lady beetles can effectively reduce the infestation of aphids in watermelon producing areas. On the other hand, biopesticide technology, as another means of biological control, is also more suitable for disease control. The principle of biological pesticides is different from that of chemical pesticides. Biological pesticides use some biologically active biological metabolites or microorganisms to remove pests and diseases, which are characterized by relatively strong insecticidal ability, low toxicity and no pesticide residues.

3. Chemical control technology of watermelon pests and diseases

3.1 Chemical control of watermelon diseases in open field cultivation

3.1.1 Fusarium Wilt

Watermelon fusarium wilt can cause a large reduction in watermelon production, and the incidence of watermelon fusarium wilt can be reduced to a certain extent through correct watermelon seed selection and flood and drought rotation. In addition, in chemical control, one method is to treat the seeds with potassium permanganate, 70% thiophanate-methyl WP before sowing watermelon. Another method is to use 50% carbendazim WP for seed dressing. In the diseased plots, the soil should be sterilized with lime, and drugs such as thiophanate-methyl WP or carbendazim WP should be used to spray the roots of watermelon seedlings to prevent watermelon wilt.

3.1.2 Phytophthora blight

The occurrence of watermelon phytophthora blight is often related to the use of organic fertilizers that are not fully decomposed and contain bacteria. Therefore, preventive measures need to start from the following aspects. First of all, the watermelon area should be alternately planted with grass crops once every three years, so as to reduce the probability of watermelon phytophthora blight caused by organic fertilizers. Then use 25% Zaoxanling WP, 90% ethylphosphine WP and other drugs to spray, once a week, 2 times in a row, to effectively prevent watermelon phytophthora blight.

3.1.3 Anthracnose

Watermelon anthracnose is more harmful, and the incidence of this disease is high in the middle and late stages of watermelon growth. In the season with more rain, special attention should be paid to the prevention and control of this disease. Using 70% thiophanate-methyl WP can make it control well.

3.1.4 Gummy stem blight

Watermelon gummy stem blight mainly damages the vines of watermelon. In order to prevent and control this disease, we must first choose varieties with strong disease resistance, and the other can use compound carbendazim gel suspension for seed soaking and 37% antibacterial spirit WP for seeds soaking. After the occurrence of diseases and insect pests, 70% mancozeb WP, 50% polysulfide glue suspension, 36% methyl thiophanate glue suspension can be used for spray control.

3.2 Chemical control of watermelon pests in open field

3.2.1 Aphids 

Aphids are common pests in open field watermelon cultivation, which mainly damage the leaves of watermelon, causing the leaves to wither and curl, causing watermelon yield reduction. 20% Quick Killer EC can effectively control aphids. It can also be mixed with sugar, wine, vinegar and pesticides in proportion to make a potion for control.

3.2.2 Leafminer

The leafminer will cause harm to the growth of watermelon in the larval stage. This pest is distributed on the upper and lower surfaces of watermelon leaves, gnawing on the mesophyll, and affecting the photosynthesis of the leaves. During the peak incubation period of larvae, the use of 48% chlorpyrifos EC, 75% carbaryl WP and other drug sprays can effectively control this pest.

3.2.3 Red spider

The red spider mainly damages the stems and vines of the watermelon. After the watermelon is eaten by the red spider, it will cause water loss, the stems and leaves of the watermelon will turn white and curl, and there will be many small white spots on the leaves of the watermelon leaves, and eventually the plant will wither. To prevent and control red spider spider, mainly use 10% Benbutaben EC or 10% Benbutaben EC and Emamectin EC mixed and sprayed, and carry out the second medication at an interval of 7-10d.

4. Basic principles of chemical pesticides controlling watermelon diseases and insect pests

Watermelon is an edible plant. If there is an error in the use of chemical pesticides, it will lead to pesticide residues and cause uncontrollable harm. Therefore, when controlling the pests and diseases of watermelon cultivated in the open field, it is necessary to use pesticides rationally in accordance with scientific methods. The rational use of drugs includes the following three aspects.

4.1 Prescribe the right medicine

At present, chemical pesticides are the best way to control watermelon pests and diseases, but chemical pesticides have limitations. One pesticide often only has a good control effect on targeted pests and diseases, and has no effect on other pests and diseases. In addition, chemical pesticides are relatively toxic, which will lead to pesticide residues in watermelons. Therefore, pesticides must be selected accurately to effectively prevent pests and diseases while avoiding the problem of pesticide residues. In addition, some pests and diseases can also be controlled by non-chemical pesticide methods. For example, no pesticides are used for fusarium wilt, and the disease can also be controlled by grafting.

4.2 Reasonable concentration

In order to achieve the best effect of chemical pesticides, the concentration of pesticides must be reasonably determined. If the concentration is too low, the effect of removing pests and diseases will not be achieved. If the concentration is too high, the quality of melons and fruits may be affected while eliminating the pests and diseases, and even the health of humans and animals will be threatened. Therefore, when using pesticides, be sure to follow the instructions of the drug insert and different drug use methods to carry out the ratio. If drip irrigation is used, the concentration should not exceed 1:220. If the concentration is too high, the watermelon root system will be damaged by pesticides. In the middle and late stages of watermelon growth, the concentration can be increased, because in the middle and late stages, the root system of watermelon is not as fragile as the seedling stage. In the late stage of watermelon growth, the concentration can reach 2 times that of the previous stage, but pay attention, the number of times of medication should not be too much, otherwise it will also affect the growth of watermelon.

4.3 Mixed use of pesticides requires caution

Farmers often unilaterally think that the mixing of pesticides is a simple superposition of efficacy, but not all pesticides are effective when mixed. The following points should be paid attention to when mixing pesticides: (1) The pesticides used in mixing should not be chemically changed. (2) Mixed pesticides cannot increase toxicity. (3) The physical properties of the mixed pesticides should remain unchanged. (4) Mixed pesticides should have different mechanisms of action or different control objects.

5. Conclusion

In the face of the current problems of the main diseases and insect pests of watermelon cultivated in open field, although several physical, chemical and biological treatment methods are proposed in the above article, but in the face of the large area, variety and long time of watermelon planting in the world, the existing treatment methods often fail to achieve results. We hope to inspire better control methods, promote watermelon planting, and promote the further development of the entire crop industry chain.