Five measures to prevent sunflower head disease
Sunflower sclerotinia disease, commonly known as white rot disease, bad head disease, is a frequent disease in our province, but also the greatest threat to the province's sunflower production. Can cause the stalk to break, the disk and the seeds rot, have a great impact on the yield. The main symptoms: sunflower sclerotinia can occur in each growth period. During the seedling stage, seedlings will suffer from brownish flooding and large spots at the base of the seedling. When the air humidity is high, the disease minister will produce a white flocculent hyphae and later produce a black sclerotia. After the disease spot surrounds the stem, the upper part of the disease will lose water. The seedlings withered and died. In the adult plant, when the middle and lower parts of the stem are susceptible, a brown pitted ulcer spot is produced. After the spot is expanded, the plant is easily broken. The pith has black sclerotia, and the water loss of the stem is grey and broken. After the disk was damaged, a water-soaked lesion appeared behind the disk, which later turned brown and rotted, forming a black sclerotia. After the disk rots and falls off, the light stalks remain. The lightly damaged flower discs have small seeds and are dull, and the epidermis is shed. Most of the seeds cannot germinate. Therefore, the prevention of bad head disease should take the following measures. First, early harvest in phases. After the beginning of September, the sunflowers began to ripen, but due to different varieties, or uneven seedlings can cause early and late differences between mature plants, do not be very large, and some even a difference of 10-30 days, that is, the varieties of pure varieties are also different 25 days or so, and the key to the loss of rotten discs is still concentrated within the first half of the maturity period. Therefore, timely and early income by stages is an effective measure to reduce the loss of rotten discs. The best standard for timely harvesting: yellowish-brown on the back of the disk, yellow stems on the plant, most leaves yellow off; stipules brown, velvety tongue fall, tubular flowers withered, grain harden, reproduce the varieties Features the best harvest period. According to tests, sunflower harvested only lost 1.4% of the crop when it was generally mature, and delayed 5.4% for a 5-day harvest, a 6.1% for a 15-day delayed harvest, and a 12.3% for a 25-day delay. Therefore, early harvest in stages should be timely and timely, to reduce the loss of sunflower, but also to avoid the occurrence of bad disk, to achieve both. Second, clear field strains. During the growing period, if a diseased plant is found, it must be removed, burned or buried deeply. After the harvest, the rotten discs in the sick bodies in the sunflower fields, especially on the ground, should be completely removed and burned out of the fields. We must not use fertilizers such as Kwai-par, to prevent the spread of sclerotia. Third, pick up the bad dish. After the harvest, qualified peasant households should organize human resources to pick up rotten discs and focus on burning them outside the fields. This is an important measure to reduce the source of bacteria. Fourth, chemical control. The use of sikling, vinyl nucleus or sclerotin net, diluted 500 times, at the end of flowering hollyhock and 10 days after the end of flowering spraying effect is good, once the drug is 1.5 kg/ha, sprayed on the flower plate Front and back. 5. Deeply extinguish the seedlings. For conditional farmers, the sclerotia can be buried in the soil by 7 cm deep; the occurrence of sclerotia can be prevented. One-time deep fall more than 20 cm in autumn, can control germination germination spread next year.