Comprehensive control of fennel root nematode disease

Fennel is a perennial herb, cultivated for one or two years. The whole plant has a special spicy smell and white powder on the surface. Leaves pinnately divided, lobes linear. Yellow flowers in summer, compound umbels. Fruit oval, yellowish green. Sex likes warmth, which is suitable for the growth of sandy loam. It is forbidden to plant in clay and wet land. It can be sowed in spring and autumn or propagated separately in spring. Native to the Mediterranean region, it is widely cultivated in various parts of our country and has strong adaptability.

What are the types of fennel?

Fennel is also known as fennel seedling. It is a 1 ~ 2-year herb of Umbelliferae. The whole plant has a special fragrance, mainly for stuffing, but also can be fried. There are different types of fennel, such as cumin, fennel and bulb fennel.

(1) cumin: the plant is relatively short, with a height of 20cm and 35cm, with 7-9 leaves, short petiole, small leaf spacing, slow growth and late bolting. There is a difference between round seed and flat seed of cumin. The round seed has shorter growth period, earlier bolting and lower yield, while the flat seed has strong adaptability, late bolting and strong regeneration ability. Cumin is mainly cultivated in various parts of Shandong Province.

(2) fennel: plant height 30mm 45cm, leaf number 5cm, petiole longer, leaf spacing larger, fast growth, early bolting. Shanxi, Inner Mongolia and other provinces (regions) more cultivation of fennel.

Comprehensive control of fennel root nematode disease

Fennel root-knot nematode disease symptoms:

Fennel root-knot nematode disease occurs only in local areas, but the incidence is high, generally more than 50%, and the most serious up to 100%. Root-knot nematode disease can damage not only Umbelliferae vegetables, but also Cucurbitaceae, Solanaceae, Cruciferae, Compositae, Chenopodiaceae and other vegetables.

Symptom recognition

The injured plant has no obvious symptoms in the aboveground part, sometimes withered or poor growth, in the underground, lateral root and whisker root have root knot of different size (also called tumor), cut open the root knot, there are very small milky nematode. In serious cases, the seedlings wither and die.

Key points of identification: there are many nodular root knots of different sizes in the root.

Incidence regularity of fennel root-knot nematode disease

1. The pathogen fennel root-knot nematode is caused by root-knot nematode infection. The female and male bodies of the pathogenic nematode are different, the larvae are slender worms, the male adults are linear, and the female adults are pear-shaped, white or colorless and transparent. Each female adult can lay 300-800 eggs, buried in the root knot tissue and fixed.

two。 The infected circular root-knot nematode overwintered as the 2nd instar larvae in the soil, and the eggs or scattered root knot (diseased remains) excreted by the aged larvae could survive in the soil for 1-3 years. When the temperature rises to about 10 ℃ in the second year, the overwintering eggs hatch into larvae, invade from the tender roots and secrete growth hormones such as indole-acetic acid, which makes the root cells proliferate to form giant cells, also known as root knots. After several peeling, the female larva mated with the male to lay eggs at the 4th instar, while the male left the host and entered the soil and died soon. The egg hatches the first instar larva in the root knot, leaves the oocyst after the 2nd instar, and enters the soil to find the root system for re-infection. Nematodes are mainly transmitted by diseased soil, diseased roots and irrigation water. in addition, people, animals and farm tools can also be transmitted and infected repeatedly.

3. Disease condition

The main results are as follows: (1) the relationship between disease and temperature: when the soil temperature is 20 ℃, the nematode begins to damage, and when the soil temperature is 25-30 ℃, the damage is serious; when the soil temperature is below 10 ℃, the larvae stop activity, more than 40 ℃, a large number of larvae die, and the lethal temperature is 55 ℃ for 10 minutes.

(2) the relationship between disease and soil moisture is suitable for nematode reproduction. The soil moisture suitable for nematode reproduction is 40%. If the soil moisture is too large or too small, the nematode activity and reproduction are inhibited.

(3) the relationship between disease and cultivation; in addition, the loose sandy loam soil with moderate soil moisture and good ventilation is suitable for nematode activity, and the damage caused by organic fertilizer with nematode is also serious.

Pollution-free control of fennel root-knot nematode disease:

1. Agricultural prevention and control

(1) rotation with Liliaceae vegetables for 3 years, or rotation with wheat, corn and millet for 2 years, or rotation with aquatic vegetables or rice for 1 year.

(2) strengthen the management of clay planting, apply sterile organic fertilizer, bury or burn the diseased roots and diseased seedlings outside the field, and disinfect or scrub the farm tools used in the diseased land so as to prevent the spread of human and livestock.

two。 Physical prevention and control can be carried out during the period of high temperature and leisure in three summers. The method is: first, clean the countryside, thoroughly remove the root of the disease out of the field and burn it. The second is to apply 50kg of lime every 666.7 square meters, plus 500kg of rice straw (chopped) or wheat taro, evenly applied to the surface. The third is to dig 50 cm deep into the soil. Fourth, the ridge is 30 centimeters high. Fifth, ditch irrigation, watering every day, always keep the ditch full of water. Sixth, covered with plastic film, closed greenhouse or greenhouse for 10-15 days, after soil separation and determination, the effect of killing nematodes reached more than 90%.

3. Ammonia fumigation before sowing or planting, every 666.7 square meters of liquid ammonia 50-60 kg, with mechanical operation, operators should wear goggles, masks, gloves and so on. After application, cover the plastic film and seal for 7-10 days, then remove the film, turn the soil deeply, ventilate and deflate, and then turn the soil for ventilation 3 days later, until there is no smell of ammonia, it can not be sown or planted after 10 days, otherwise ammonia will poison the seedlings.

4. Before sowing or planting the pollution-free pesticide, the diseased field can be treated with 18% Aifuding EC or 1.8% acaroid EC, 1-1.5ml per square meter of ditch, and then covered with soil. at the initial stage of the disease, 1.8% Aifuding 3000 times solution was used for root control.

Chemical control of fennel root-knot nematode disease:

1. The soil disinfection area can be disinfected with a mixture of 55% Didi D (40 kg per 666.7 square meters). Before sowing or 15-20 days before planting, the land is ploughed, and then ditched every 60 cm, 20 cm deep, evenly applied into the ditch, and then covered with soil compaction. Hole application is also possible, first cultivated, hole spacing and row spacing are 30 cm, hole depth is 15 cm, each hole is filled with 3 ml dilution solution, and then compacted with soil. After 15-20 days of covering with plastic film, uncover the film and turn the soil deeply, ventilate and deflate, and then sow or plant a few days later. 3% milol granules can also be used, 5 kg per 666.7 square meters before sowing or planting. Or use 33% Weibai water agent, 3-4 kg per 666.7 square meters, add 75 kg of water, ditch and pour, and then cover the soil and step on it. Or use 10% limanku granules, 5 kg per 666.7 square meters, acupoint application.

two。 At the initial stage of the disease, 50% phoxim EC 1500 times, or 80% dichlorvos EC 1000 times, each plant 250ml, also has a certain effect, generally only once.