Identification and Control Methods of Loose Smut of Annual Bluegrass
Annual bluegrass (Latin scientific name: Poa annua L.), also known as: small green grass, chickweed grass, cold grass, etc.; an annual or winter annual grass. Culms erect or decumbent, soft in texture, 7-30 cm tall, entirely smooth and hairless. Leaf sheaths slightly compressed, closed below the middle; ligule 1-3 (-5) mm long, rounded at the tip. It grows on roadsides, grasslands, field ditches, or shaded waste slopes in plains and hills, at an altitude of 100-4800 m. It is distributed in all provinces of northern and southern China, as well as in Europe, Asia and North America. It is a globally widespread weed that requires strict management and control.
Main values of annual bluegrass
Landscaping: This herb is a high-quality cool-season turfgrass widely used in temperate zones, and lawn greening in the north has huge development potential. Its well-developed rhizomes, extremely strong tillering ability and long green period and other excellent traits enable it to rapidly form a dense and neat lawn. Generally, a single transplanted plant can form more than 100 new shoots after 3 months; after 5 months of growth and propagation, it can expand to an area of 60 cm x 60 cm. In severe winter, it can overwinter without cover. In temperate zones, it withers only when the temperature reaches -2 to 5°C in December. It can also tolerate dry and hot summers. It can grow well at a high temperature of 38°C. It turns green around March and withers in mid-December, with a green period of 9 months, making it the most important grass species for northern grassland lawns. It can be used to build green sports fields, golf courses, parks, roadsides, dams, etc. This species requires a high level of management, and the lawn quality is high when mowed at a height of 0.5 cm. In this region, it can be used for winter overseeding of warm-season turfgrasses.
Forage: This grass is an important grazing gramineous forage. It has a long grazing period, is resistant to trampling, and has high nutritional value. From early spring to autumn, it is rich in nutrients, and all kinds of livestock like to eat it. During the milk-ripe seed stage and the green grass stage, horses, cattle and sheep like to eat it; in the late mature stage, cattle and sheep still like to eat the upper stems and leaves; during the summer and autumn green grass period, it is a fattening grass for yaks, Tibetan sheep and goats; hay is supplementary forage for livestock, and it is also good feed for pigs and poultry. It can also be fed to small parrots such as budgerigars and lovebirds. You can pull a few stalks in your own neighborhood, as there are generally many annual bluegrass plants there. However, it cannot be used as the main feed.
Medicinal use: Pharmacological effects - hypoglycemic effect: Subcutaneous injection of an extract of Kentucky bluegrass into normal fasted rabbits significantly lowered blood sugar, with the most obvious hypoglycemic effect 3 hours after administration, and its action characteristics are similar to insulin. When an extract equivalent to 40 g of crude drug was injected into humans, glucose tolerance increased from 40 g to 100 g, and the effect of increasing glucose tolerance remained for several days after discontinuation. After patients took this drug, urine sugar was significantly reduced, but there was no obvious effect on the excretion of ketone bodies in urine. The extract can also accelerate the glycolysis process of yeast, and its effect is similar to that of vitamins and may be unrelated to insulin. Functions and indications: Lower blood sugar. Mainly for diabetes.
Introduction and control of loose smut of annual bluegrass
Loose smut is an important disease on annual bluegrass and occurs widely in various planting areas, affecting the yield of annual bluegrass and some other grasses as well as seed quality. Symptoms of loose smut of annual bluegrass:
Diseased spikes are twisted and deformed, and the ovary is filled with black powdery teliospores. The outer covering breaks easily, leaving only the rachis. Pathogen of loose smut of annual bluegrass:
Ustilago trebouxii H. Syd. is called Elymus smut, belonging to the Basidiomycotina fungi. Spores spherical to oval, light olive-brown, minutely spiny, sometimes smooth, darker on one side with more obvious spines, 3.5-5μm×3.5-7μm. Most are 4-5μm. In addition to infecting several species of Poa, it also infects Elymus, Hordeum, Puccinellia, Agropyron and Stipa. Occurrence characteristics of loose smut of annual bluegrass:
The pathogen overwinters as teliospores in the soil or adhering to the seed surface. The following spring, after germination, it infects the coleoptile of seedlings and reaches the inflorescence as the plant grows, producing spore piles. Under room temperature and dry conditions, teliospores can survive for as long as 10 years. Control methods of loose smut of annual bluegrass:
1) Select and plant disease-resistant varieties according to local conditions.
2) Strengthen grassland management. Sow at the appropriate time and maintain reasonable planting density; manage fertilizer and water scientifically to improve plant disease resistance and prevent lodging; graze moderately and harvest at the appropriate time, and after harvest remove diseased and residual tissues in the field to reduce inoculum sources for the coming year.
3) Seed treatment. ① Hot water seed soaking. Soak seeds in warm water at 53-54°C for 10 minutes, with the water amount being 20 times the seed amount; after soaking, spread out to dry. ② Chemical seed dressing. Seed dressing with carboxin (effective ingredient 3 g per seed lot) and thiram (12 g) can effectively control this disease. Captan, benomyl and oxycarboxin are also very effective. Commonly used agents: carboxin, thiram, captan, benomyl, oxycarboxin