Avocado tree root rot disease 28/10/2021

Ph.D. Nguyen Minh Tuyen

Avocado is a fruit with high nutritional value, very beneficial to human health, so it has been favored by many people. Growing avocados has also brought great sources of income for farmers, as well as contributed to enriching Vietnam is tropical fruit brand. Therefore, in recent years, avocado trees have been planted on a fairly large area in the Central Highlands provinces. However, due to investment in intensive cultivation of avocado trees spontaneously, on a large area, many pests have arisen. One of the most dangerous pests that has killed trees in large numbers, causing production difficulties and increasing costs for farmers, is avocado root rot.

* Symptoms of the disease:

When getting diseased, the most common symptom is the plant is weakness, the leaves are yellow and fall, sometimes see oozed sap in the main trunk close to the base. If you dig around the root zone, the roots will rot. When the disease is severe, the main root part will be black and wet rot. The lesion will spread horizontally and vertically, When the lesion develops, embraces the entire circumference of the bark at the base or at the main roots, the tree will drop its  leaves at the same time and die.

 

* Pathogens and conditions of development:

Avocado root rot is caused by Phytophthora sp fungus

In conditions of high density planting, digging deep holes to make high-mouthed pits for planting , planting low, so water stagnates at the base, fertilizing with excess nitrogen, plants are too green, luxuriant, low branches touch the ground, the garden is shaded by other trees, full mulch the tree base during the rainy season, the drainage system is poor... Then the disease will definitely be very serious

The principle is to apply a combination of many possible measures.

- Plant trees with appropriate density.

- Make beds in the east-west direction so that each plant can receive sunlight throughout the day.

- Do not dig deep holes to make high-mouthed pits for planting, but should be planted high, Raise the root to ensure that the roots are dry after rain or watering. If necessary, make raised high-mouthed pits for planting, around the root still need to cover the soil to drain. Should whitewash the tree trunk close to the ground.

- Do not irrigate with a drip system directly at the base of the tree, but only water the area around the canopy to keep the root dry.

- Do not closely mulch the root in the rainy season and need a good drainage system.

- Cut off branches sweeping the soil, infected branches in the canopy so that the garden is well ventilated.

- Apply decomposed organic fertilizer and cover with the antagonistic Trichoderma sp fungus as possible.

- Apply lime or CALCIUM NITRATE to ensure adequate supply of Calcium for plants, helping to increase the resistance of plants.

- Fully balanced fertilizer application, not excess nitrogen.

- Use TANO 601 fertilizer to provide necessary micronutrients for plants.

- Check the orchard regularly to detect diseased trees for timely treatment.

When detecting diseased plants, it is recommended to combine spraying the whole plant and watering the roots with MEXYL MZ 72WP or TREPPACH BUL 607SL to prevent disease. Incorporate preventive treatment for neighboring plants to avoid disease transmission. During the rainy season, it is advisable to proactively prevent disease in advance to help reduce the cost of prevention.

 

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