One of the prevention and control methods of watermelon diseases and insect pests

Anthracnose is a fungal disease, which mainly harms watermelon and muskmelon. The disease can occur in the growing season and post-harvest storage and transportation, especially in the middle and later stage of growth.

After the onset of the seedling stage, there were brown round or semicircular disease spots on the edge of the cotyledons, black dots or reddish sticky matter on the top, and the seedlings were quenched. The leaves were initially water-stained spindle-shaped, round light yellow disease spots, soon turned into black round spots, there was a purple circle on the periphery, and there were concentric wheel patterns. The disease spots on the stem vines and petioles are oblong, slightly sunken, first watery yellow-brown, and then black. Dark green oil-soaked spots appeared at the beginning of the fruit, and after enlargement, they were round or oval-shaped depression, dark brown, and there were many small black spots arranged on the spot. When it is wet, it overflows with pink sticky matter, and most of the young fruits become deformed after they are infected. The pathogen overwinters on the diseased remains in the soil or on the seeds, and the seeds can directly invade the cotyledons.

The control measures are as follows: rotation for 3-4 years without bacteria-carrying fertilizer. The seeds were soaked in 100-fold formalin solution for 30min, washed and then germinated, or 5min was soaked in 55 ℃ warm water. Increase the application of phosphate fertilizer, potash fertilizer, pay attention to drainage, melons and fruits under the grass cushion melon. At the initial stage of the disease, diseased leaves and vines were removed and buried deeply. Spray 1000 times of 50% carbendazim, or 100% Bordeaux solution of 1v or 600 times of 75% chlorothalonil, spray once in 7 days and 3 times in a row.

Fusarium wilt can occur in all growing periods, and the most common disease occurs in the middle stage of melon extension. Cataplexy occurred in the seedling stage. The lower part of the adult plant yellowed when the disease occurred, wilted during the day at the initial stage of gradual upward development, recovered sooner or later, and the whole plant withered a few days later. The stem and root system showed water-soaked rot, browning, sometimes pink mildew, and the vascular did not turn brown.

The bacteria survive in the soil for 5 ~ 6 years, and the bacteria can still remain alive after passing through the digestive tract, so barnyard manure can also carry bacteria. The pathogen invades through the root wound or the top of the root hair, develops in the duct, affects water transport and causes plant wilting. Low-lying terrain, poor drainage, lack of low fertilizer, too much nitrogen fertilizer, serious disease during flood irrigation and continuous cropping.

The prevention and control measures are as follows: 7-8-year rotation. The diseased plant was immediately removed and burned, and 50% Dysenamine 400 times solution was used to disinfect the disease point. Select disease-resistant varieties, use pumpkin or gourd as rootstocks for grafting, or irrigate the rhizosphere with 70% dimethazone powder, 200 ~ 250ml per plant. It can also be made into a paste with 1 part of dimethazone powder and 20 parts of flour and smear the base of the stem of the diseased plant.

Small land tigers are also called soil silkworms and root cutters. There are 2-7 generations a year, and the harm of the first generation is serious in most areas. adults live in weeds or soil cracks during the day, feed at night, mate and lay eggs, and the adults have strong chemotaxis and phototaxis. The larvae have a total of 6 instar, and before the 3rd instar, most of them feed on the host heart leaves or soil surface and soil crevices, and feed on the host tender leaves day and night. The 4th and 6th instar larvae lurk in the soil during the day and do harm at night, biting off the tender stems or heads of the seedlings on the ground. The suitable temperature for the growth and development of small land tiger is 13-25 ℃, and the soil water content is 15%-20. The area with low-lying terrain, heavy soil viscosity and overgrown weeds is seriously harmful. Ploughing the land in winter and spring to destroy some egg blocks, overwintering pupae and larvae. In the early morning, the topsoil near the broken seedlings was artificially removed to kill the advanced larvae. Trapping and killing with paulownia leaves, collecting fresh paulownia leaves and soaking them in water, then releasing them in the victimized field in the evening of the first generation of larvae, relying on a certain smell from paulownia leaves to entice tigers to feed. It can also be trapped with fresh vegetable leaves or small piles of weeds. When the worm is older, the root is irrigated with 50% diazinon emulsion 1000-1500 times, or 50% octane sulfuric acid EC.

Both adults and larvae of Huangshou melon can be harmed, and the larvae bite the fine roots or drill into the pith and the stem near the ground, resulting in poor growth of seedlings, yellow wilt and even death. Adults eat harmful leaves, flowers and fruits, bite into many round or semicircular notches, suffer heavily in the seedling stage, and often eat all the leaves.

Manual hunting early in the morning when the dew is not dry. Use plastic film cultivation, or sprinkle plant ash, chaff, sawdust and so on around the plant to prevent adults from spawning and reduce larval harm. Spraying 2000-fold solution of trichlorfon to control adults and 2000-fold solution to root can kill larvae. In addition, there are melon aphids and ground maggots.