Control measures of Cotton Seedling Diseases in Binzhou City

There are many kinds of diseases in cotton seedling stage. The most serious diseases in cotton seedling stage in our city are blight, anthracnose and red rot. In recent years, especially the first two diseases are more serious than in previous years. Doing a good job in the prevention and control of cotton seedling diseases is the key to the increase of cotton production and income in our city. At present, the key to the prevention and control of cotton seedling diseases is to implement the plant protection policy of "prevention first, comprehensive control".

1 symptoms of cotton seedling disease

1.1 the obvious symptom of the disease in the field is the long yellow-brown spot on the root of the cotton seedling and the base of the stem near the ground. the serious disease spot expands to dark brown and causes circular constriction around the whole rhizome, resulting in the death of the whole plant and the root rot of the dead plant. When the cotyledons were damaged, irregular yellowish-brown disease spots were produced on the injured leaves, and the disease parts dried up and fell off to form perforation.

1.2 the disease of anthracnose in the field is mainly manifested in the brown stripes on the rhizome and stem base of the seedlings, which are seriously split and sunken longitudinally, resulting in the vascular bundle not being able to absorb water normally and the seedlings die. The damage of cotyledons often produces semicircular or near-semicircular brown markings on the edge of the leaves, which can be extended to the whole cotyledons when the air humidity in the field is high. Most of the damage to the stem occurred from the leaf scars, forming black round or long sunken spots.

1.3 the disease of red rot mainly occurred in the rhizome in the field. The injured stem shows swelling, and then becomes dark brown and dry rot, which is what people call "Bigfoot seedlings". Cotyledons often produce round or irregular brown spots at the edge of the leaves. When the humidity in the field is high, the red enzyme can be seen in the disease site.

2 prevention and control measures

2.1 Agricultural control measures

2.1.1 cultivation and management ① removes the disease and residue in the field in time. The diseased and disabled bodies in the field of the previous year should be removed before sowing to prevent the bacteria lurking on the diseased and disabled bodies from invading again. ② chooses a good time for cotton sowing. Because the soil temperature is too low, the seeds delay the unearthing time and reduce the disease resistance. In addition, do not sow too late, so as not to affect the yield of cotton to be harvested. The sowing depth in the field is about 4~5cm, and the above is covered with plastic film. According to the weather and soil moisture flexible control, windless weather, soil moisture can be shallow, otherwise it should be deeper. In dry and windy areas, small ridges are raised in cotton rows when covering soil after sowing, which is beneficial to preserve soil moisture, prevent rain and help seedlings unearthed. ③ field management. After emergence, it is necessary to plough the field and loosen the soil in time, pay attention to ploughing after rain, prevent soil consolidation, and indirectly improve soil temperature and plant disease resistance. ④ should have a reasonable rotation. Practice crop rotation with other crops for more than 3 years as far as possible.

2.1.2 seed treatment ① selected varieties with full seeds, high germination rate and strong germination potential. Remove rotten seeds, insect seeds, blighted seeds, miscellaneous seeds and so on. ② seeds were treated with chemicals before sowing. Soak the seeds, remove and dry them until the hairs turn white, then mix the seeds according to the ratio of seed: grass ash: carbendazim 100 ∶ 10 ∶ 0.5. The method is that the medicine ash is fully mixed and mixed into the cottonseed, fully rubbed, so that the medicine ash is uniformly attached to the seed surface; the seed can also be mixed with 75% pentachloronitrobenzene according to the seed amount of 0.5%; 0.3% methyl chlorophos, 2.5% suspension seed coating agent and so on can also be selected. Soak the seeds in ③ warm soup. Pour the seeds into 70 ℃ warm water and stir up and down, keep the water temperature 55-60 ℃, soak the seeds for 30 minutes, remove and dry until the hair is white, then sow the seeds.

2.2 Chemical control measures 50% thiram and 70% mancozeb can be used in seedling stage. After emergence, spray with 1 ∶ 1 ∶ Bordeaux solution or 50% trimethoprim 800 × 1000 times solution, generally spraying 2 times 4 times at the seedling stage, with an interval of 7 days, or with 50% carbendazim or 70% topiramate 1000 times solution at the initial stage of the disease.