How to control the leaf spot of Sudan grass

Sudan grass alias wild sorghum, is an annual herb, can adapt to the same environment as sorghum, only mature earlier. The fibrous root, the root system is well developed, the depth of the soil is more than 2 meters, the average distribution is 75 cm, and the root system is distributed in the tillage layer. Sudan grass has good regeneration, which is an important reason for its multi-cutting and high yield. After cutting, the regenerated branches can be produced from three parts: the tillering node, the first basal stem node and the branches whose growth point has not been destroyed, but more than 80% of the regenerated branches are formed by the tillering node, and the rest are formed by the first stem node at the base of the stem. The cutting height of Sudan grass is directly related to the regeneration ability. generally, the stubble height is 7 to 10 cm, and the stubble is too low to affect the regeneration.

Sudan grass is not strict to the soil, as long as the drainage is smooth, it can be planted on sandy loam, heavy clay, weak acid and light saline soil (soluble sodium chloride is 0.2% to 0.3%), while fertile chernozem and dark chestnut soil grow best. Grow poorly in soils that are too moist, poorly drained, or over-acidic or over-alkaline. It can also be planted on sandy soil, but the yield is low.

Geographical distribution of Sudan grass

The steppe of Sudan comes from the highlands of Sudan in Africa. Widely cultivated in Europe, North America and the Asian continent. China was introduced before liberation, and now there is a large area of cultivation in the north and south provinces. After years of cultivation experiments and small-scale planting, it is proved that Sudan grass has extensive adaptability, which can be cultivated as far as Hainan Island in the south and Inner Mongolia in the north.

How to prevent and cure Sudan grass leaf spot?

Leaf spot is an important disease on Sudan grass, which is widely distributed at home and abroad. It also infects maize and sorghum plants, causing serious damage. Symptoms of Sudan grass leaf spot:

The disease spot is mainly damaged leaf, the leaf spot is long fusiform, the size is 20-60mm × 4-10mm, the edge is watery, the center is withered yellow to brown, the edge is purple in the later stage, black mildew can be seen on both sides of the leaf spot, that is, the conidiophores and conidia of the pathogen, and the whole leaf dies in severe cases. Disease spots can also occur on leaf sheaths and bracts. The pathogen of Sudan grass leaf spot:

Bipolaristurcicum (Pass.) Shoemaker is called Alternaria maculata, HelminthosporiumturcicumPass., which belongs to the subphylum of semiknowns. There is no sexual generation in nature. Conidiophores protruding from stomata, 2-6 clumps, olive-brown, 2-6 septum, 12.5-188.7 μ m × 7.5-10.0 μ m, base dilated, spore scar obvious, born at the apex or geniculate flexion. The conidia are fusiform, olive brown, straight or slightly curved, and the basal cells have obvious umbilical points, protruding, 2-8 septum, mostly 4-7, and the size is 45-140.6 μ m × 15-25 μ m. The spores germinate from the cells at both ends to produce germ tubes. Characteristics of leaf spot of Sudan grass:

The pathogen overwintered on the diseased and residual plants with dormant mycelium and conidia and became the source of field infection in the spring of the following year. Spores are transmitted by wind and rain and invade by epidermis or stomata. The suitable temperature for mycelium growth was 27-30 ℃, and the temperature range was 5-35 ℃. The temperature of spore formation is 11-30 ℃, and the optimum temperature is 23-27 ℃. The suitable temperature for field epidemic is about 25 ℃. After spore invasion, spores can be produced on the disease spot in 10-14 days. Spore germination requires rainy and foggy weather, with a relative humidity of at least 60% and 70%, and a liquid water film on the leaf surface. The disease resistance of new leaves was stronger than that of old leaves, and the disease of seedling or young plants was lighter than that of adults after heading. Control methods of leaf spot of Sudan grass:

1) breeding and planting disease-resistant varieties according to local conditions.

2) strengthen grassland management.

Timely early sowing, try to avoid high temperature and rainy period; reasonable close planting to prevent over-dense lodging; scientific fertilizer and water management to improve plant disease resistance; moderate grazing, timely harvest, complete removal of field residues after harvest.

3) Pesticide control.

Scientific research sites and seed fields can be protected by fungicides such as Mai Sui Ning, Mian Wei Ling, Tuijute, methyl topiramate or Dysen zinc, thiram and other fungicides.

Commonly used medicament Mai Sui Ning, Mian Wei Ling, Tuibu Tate, Methyl Topurazine, Dysen Zinc, Thiram.