SAP BLEEDING AND TRUNK CRACKING DISEASE ON CITRUS 21/06/2023

SAP BLEEDING AND TRUNK CRACKING DISEASE ON CITRUS

 

Currently in Vietnam, the cultivation of citrus trees is playing an important role in the country agricultural production. The benefits of citrus trees have made many farmers rich. However, wherever citrus trees are planted, fissured trunk cracking appears and causes damage. If any gardener is negligent or lacks attention to this disease, the tree will die, even the whole garden.

Disease symptoms:

When diseased, the most common symptom is sap ooziness  on the main trunk at the position close to the base. However, the disease also appeared on other sites in the trunk and branches. When the disease is severe, we see that the bark of the trunk is cracked, the disease spreads gradually horizontally and vertically, and the growth and plants grow and develop slowly. If the lesion grows large, damaging the bark at the base or at the branch, the whole tree or branch will die.

Pathogens and conditions of development:

Sap bleeding and trunk cracking disease caused by Phytophthora sp.

In conditions of high density planting, dig a low planting hole so water stagnates at the base, fertilize with excess nitrogen, the tree is too green, luxuriant, low branches touch the ground, the garden is shaded with other trees, and basal cover is closed during the season. rain, poor drainage system...then the disease will definitely be very serious.

Highly effective preventive measures:

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

Planting trees with appropriate density depending on the variety (eg,  Sành oranges have a higher density than Giấy oranges).

Make beds in the East-west direction so that they can receive sunlight throughout the day.

Do not dig holes for planting, but should be planted in beds, high up the roots to ensure that the roots are dry after rain. Should whitewash the tree trunk close to the ground.

Do not cover the base closely during the rainy season and need a good drainage system.

Cut down branches that sweep the ground (will be scratched in the wind and susceptible to disease), pruning infected branches in the rainy season to keep the garden open.

Fertilize with decomposed organic fertilizer and incubated with the Trichoderma sp antagonistic fungus. the better.

Apply lime or CALCIUM NITRATE to ensure an adequate supply of Calcium for the tree, help increase resistance, prevent cracking of trunk and fruit.

 

Fully balanced fertilizer application, not excess nitrogen.

Use POLY FEED fertilizer to provide necessary micronutrients for plants.

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

When the tree is found to have oozed sap, use a sharp knife to remove the infected bark and wood, use ALPINE 80WG to sweep over the diseased area. It is recommended to combine spraying and watering the whole plant with ALPINE to prevent the whole tree. Besides, it is necessary to prevent the plants adjacent to the diseased tree to avoid spreading. During the rainy season, proactive disease prevention will help reduce the cost of prevention.

 

 

 

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Adult is a small planthopper, with a body 2-3 mm long, the whole body is ash gray, slightly greenish, the wings are opaque with many small brown spots.Eggs are oval, 0.3 mm long, have a pointed end and are attached directly to the leaf surface, leaf axils.Larvae are very small, oval in shape, newly hatched are bright yellow. Age 2 and age 3 are in green. Age 4 and age 5 are golden brown and 2 small wing sprouts.

 

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 In Vietnam, yellow leaf curl disease is very common on papaya trees, especially the disease is often severe in areas of high and continuous planting, areas with hot and arid climates. The disease has significantly reduced the yield and quality of papaya. Gardens that are infected early when the plants are young may not yield. However, up to now, many gardeners still do not know the cause and how to fix it.

 

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 This group includes species that are generally very small in size, causing damage by sucking plant sap (on leaves, fruits, branches, stems).

There are many species of mealybugs present on the group of Oranges,Tangerines,Grapefruits and Lemons (Citrus), which can be divided into 2 groups:

+ Group of sticky mealybugs with common varieties such as Lepidosaphes, Aonidiella, Coccus and Saissetia.

+ Group of flower mealybugs with common genera and species such as Pseudococcus, Planococcus and Icerya purchasi.

Dry branches and berries disease often appear to be common damage on coffee gardens during the rainy season. The disease causes death of branchs, dry fruit, severely affects the canopy structure and coffee yield if not paid attention to prevention.

  

 Pink disease commonly causes diseases on rubber plantations in the rainy season, especially on garden from 4-8 years old. This year, rubber has to go through a period of severe drought, weakening the tree, so now in tnshe rainy season it is easy to get infected. Therefore, it is necessary to pay attention to good management to avoid affecting the garden.

In recent years, the area of citrus has been expanded because it is a fruit tree with high economic efficiency. However, in order to sell at a high price, not only in quality but consumers also require the external beauty of the fruit, so pest management on citrus is a matter of great concern to farmers. The hot season is a favorable condition for thrips to develop and cause damage, affecting the commercial value of fruit.

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