Control measures of root-knot nematode disease in growing citrus

Citrus root-knot nematode disease harms citrus roots, causing root nodules of different sizes, and whisker roots form cakes, which hinders the ability of roots to absorb nutrients and reduces the absorption of roots. When the citrus was first infected by root-knot nematode, the crown did not show obvious decline. With the continuous reproduction of root-knot nematode, the damaged absorbing roots gradually increased, and the crown showed the phenomenon of poorer and weaker growth than healthy trees, that is, the phenomenon of fewer tips, smaller leaves, curling, yellowing, no luster, more flowering and less fruit hanging, and low yield. When the damage is serious, the branches and leaves fall, and the serious ones will cause the whole plant to die. The following measures must be taken to control citrus root-knot nematode disease.

First, strictly carry out quarantine to purchase seedlings should strengthen quarantine, and it is strictly forbidden to purchase seedlings that may be infected with nematodes in areas that have been affected by root-knot nematode disease. The protection of disease-free areas should be strengthened and nematodes easily transmitted to disease-free areas such as soil, fertilizer, water and farming tools should be strictly prevented.

2. Selection of disease-resistant rootstocks and breeding of rootstocks resistant to citrus root-knot nematode disease is an effective way to develop citrus planting in diseased areas. According to the local cultivation conditions, through the experiment of many kinds of suitable rootstocks, the rootstocks with strong resistance to citrus root-knot nematode disease were cultivated and screened. Through the experiment on the rootstocks of citrus root-knot nematode disease in Yangcun orange field, wine cake? {rootstocks are resistant to citrus root-knot nematode disease, while mahogany lemon and sour orange rootstocks are seriously susceptible to the disease.

Third, cut off the damaged root groups in winter combined with loose soil and sun roots, inhibit soil moisture, promote flower bud differentiation, dig deep into the soil near the roots under the diseased tree plate, and cut off the fibrous roots damaged by root knot nematode disease. Cut off the nodule and knot fibrous root mass damaged by root knot nematode disease, and retain the strong root, horizontal root and larger root without nodule and root knot. When digging, you should be careful, do not hoe randomly, try not to damage the cortex of the main and lateral roots, only cut off the damaged roots, and even a small strip of healthy roots should be retained. The principle of digging the soil is that it is deep under the tree crown dripping line and gradually shallow near the tree base. It is best not to use the original digging soil, and to spread lime, which is 1% of the amount of soil needed. 2% of the amount of soil. The diseased roots should be removed from the orchard in time and burned centrally.

Fourth, to strengthen fertilizer and water management, it is appropriate to increase the application of organic fertilizer to diseased trees at a rate of 25 kg per tree, and to fertilize the organic fertilizer and guest soil at the ratio of 1:1. It is appropriate to dig the soil in winter to cut off the root of the disease, preferably at the time of Greater Cold. At the same time, when expanding holes and improving soil in June, organic fertilizer was applied once more, irrigation was carried out according to conventional cultivation and management regulations, and other fertilizer and water management measures were strengthened to enhance the tree potential and reduce the damage degree of the disease.

5. Drug prevention and cure. When digging and cutting off the diseased root, the soil is covered and mixed with chemicals evenly. Or dig a circular ditch 15 cm deep and 30 cm wide under the crown drip line, apply the pesticide after irrigation (preferably a mixture of fertilizers that will not react with the chemical) and cover the soil. Or open a hole in the tree plate every 20ml / 30cm, inject or place the medicament at the depth of 15Mui / 20cm, cover the soil and irrigate immediately after application. The safety interval of insecticides for the control of citrus root nematode disease is three months. For the sake of safety, the insecticide should be applied in winter or early spring from 2mi to early March. You can choose to apply the following chemicals (dosage per plant). ① 80% dibromochloropropane 250x liquid 10Murray 15kg. ② 10% dibromochloropropane granule 200g. ③ 3% Milol granules 200g. ④ 10g Danguo granule 200g. ⑤ 15% Tiemiake granules 100g. ⑥ 3% carbofuran granules 150ml 300g. ⑦ 3% methyl isosinophos granules 400g. ⑧ 10% Yishubao granule 100g for chemical control. Pay attention to the application of chemicals in ditches and acupoints, must be uniform, the same amount.