Wheat cereal cyst nematode disease

English name: Wheat real cycle nematode

Heteronymous wheat oat cyst nematode

Introduction: Wheat cyst nematode is currently the most threatening nematode to wheat production. This disease has occurred in the main production areas of Hubei and North China, including Hebei, Shanxi, and Beijing. This disease only occurs in plants of the Poaceae family and mainly harms 34 species of 27 genera, including wheat, barley, oats, rye, weeds, and grains.

Harmful symptoms

[Harmful symptoms] The affected wheat seedlings are short and yellow, with short branching roots. In the later stage, the roots are parasitized and form nodules, revealing white to dark brown powdery vesicles, which are typical features of this disease. Cysts are prone to shedding when they mature, and they only appear during the adult stage, so they are often misdiagnosed due to the absence of cysts during production. After being damaged by nematodes, the diseased roots are often damaged by secondary soil fungi such as Fusarium oxysporum, causing root rot. Or it may cause joint damage with nematodes, exacerbating the degree of damage, resulting in stunted and yellowed aboveground parts, resembling a lack of nutrition or water. Attention should be paid to differentiation. [Infection] One generation is born every year. When the soil temperature is above 9 ℃, it is beneficial for nematode hatching and invasion of the host. The 2nd instar larvae invade the tender root tips, insert their heads, and settle near the vascular bundles to feed, stimulating surrounding cells to become giant cells, gradually developing into pods, molting to form long necked bottle shaped 3rd instar larvae, gourd shaped 4th instar larvae, and then becoming lemon forming insects. The male adult changes from a settled type to an active type, and dies after rooting and mating with the female. The female is filled with eggs and embryonic eggs, which turn into brown cysts and then die, causing the infected roots to bulge. Eggs can remain active in soil for one or several years. After losing their life, the cyst falls off and winters in the soil, which can spread through water flow, wind, agricultural machinery, and other means.

Pathogens

The pathogen is the oat cyst nematode Heterodera avenae Wollenweber, belonging to the genus of cyst nematodes. The female insect's cyst is lemon shaped, dark brown in color, with a double membrane pore on both sides of the pubic cone and no lower bridge. There are many irregularly arranged vesicular protrusions below, with a body length of 0.55-0.75mm and a width of 0.3-0.6mm. The oral needle length is 26? m. Head ring pattern with 6 circular lips. After the 4th instar, the male worm is linear, slightly blunt at both ends, 164mm long, with a circular base outside the mouth, 26-29 in length? M; The larvae are small, needle like, with a blunt head and a pointed tail, and a mouth needle length of 24? m. The elongated labial disc merges with the sub dorsal and sub abdominal lips to form a cylindrical structure with rounded width at both ends. Egg kidney shaped, contained within the female insect body but not produced.

Occurring factors

[Law of occurrence] Spring wheat can develop cysts after being invaded for two months. Autumn wheat invades in autumn, overwintering in the roots with various developmental insect states. The following spring, the temperature rises and causes damage, revealing the cyst from April to May. It can also hatch and invade the host again, causing severe infection during the seedling stage. Generally, spring wheat is heavier than autumn wheat, and early sowing of spring wheat is heavier than late sowing. Winter wheat late sowing causes mild disease. The disease is severe in continuous cropping wheat fields; Lack of fertilizer and heavy drought in arid areas; Sandy loam soil is heavier than clay. Infection during the seedling stage has a significant impact on yield.

Prevention and control methods

(1) Strengthen plant quarantine, strictly prohibit the random transportation of seeds, and prevent the spread of this disease.

(2) Select disease resistant (tolerant) varieties according to local conditions.

(3) Improve the farming system. Crop rotation with other wheat and cereal crops every other year or three years; Spring wheat area should be broadcasted at an appropriate later time.

(4) Strengthen field management. To balance fertilization and improve plant resistance; Apply soil additives to control the rhizosphere microecological environment, making it unfavorable for nematode growth and parasitism.

(5) Seed processing. Pour wheat seeds into clean water and stir quickly. The gall rises but is removed, which can eliminate 95% of the gall. The entire operation should be completed within 10 minutes to prevent the gall from absorbing water and sinking. Using 20% saltwater to eliminate insect galls is more thorough than using clean water, but the seeds should be washed with clean water afterwards. The ammonium sulfate solution selection method can be washed with 26% ammonium sulfate solution. 50% methyl parathion or methyl isocarbophos is used for chemical treatment, and the seeds are mixed with 0.2% of the seed amount. 200g of medication is applied to 20kg of water for every 100kg of seeds. After mixing, the seeds are stacked 50cm thick and left to seed for 4 hours before sowing.

(6) Chemical prevention and control.

Source: World Agrochemical Network