PREVENTION OF PAYA LEAF YELLOWING CURLING DISEASE 21/06/2023

 PREVENTION OF PAYA LEAF YELLOWING CURLING DISEASE 23/05/2022

 

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.

 

Pathogens: Papaya leaf curl disease is caused by some viruses. These viruses are named: Papaya Mosaic Virus (PapMV), Papaya Ringspot Virus (PRSV)…

 

Way of transmission and source of disease: The pathogen is caused by a virus, so there must be an intermediary (vector) that carries and transmits the disease in order for the disease to arise and spread (vectors such as aphids, or some other sucking insects ). Aphids carry the virus from diseased plants to healthy plants. Humans can also spread the virus during planting and care. In nature, the virus can exist in many wild plants... Therefore, the source of the disease in nature is very large, so the ability to spread epidemics is always constant.

 

 Disease symptoms and effects: Depending on the virus species, the weather and the stage of infection, the time of disease onset and symptoms will be different. Usually, when infected with a virus, the plant is often dwarfed, growth and development are poor, leaves are inconsistent in color, yellow-green, mixed, mosaic, may be small, wrinkled, deformed, ... When a plant is infected with more than one virus species, the symptoms are mixed. When severely infected, the tree stops growing, has flowers but does not bear fruit, or the fruit set is very small, deformed and callused.

In the small plant stage, the earlier the virus is infected, the shorter the incubation period, and the earlier the plant develops disease. When grown trees are infected, due to higher resistance, the disease develops later. The earlier the plant develops the disease, the greater the damage. Diseased plants are often dwarfed and their leaves are curled and yellowed mosaic , so photosynthesis is reduced, fruits are reduced, thus yield and quality are reduced. If the plant is diseased early, it will not be harvested.

 

Prevention: The disease is caused by a virus, so there is no specific product to treat it. The prevention of viral diseases for papaya is quite difficult compared to other crops. However, we can manage the disease quite effectively by managing the way it is spread. To manage the disease, we must apply many measures simultaneously to achieve the desired results. Those measures are:

Clean and cut old papaya trees in the garden, clean the remnants of wild papaya trees... If possible, avoid planting near the papaya garden at a large stage, especially the old stage. Sanitize wild plants around the bank, especially since the papaya stage in the nursery.

Use varieties of papaya that are resistant to sucking pests, and resistant to viruses.

Avoid scratching the tree during planting and care.

Uproot and destroy diseased plants, do not throw diseased plants indiscriminately.

Avoid over-fertilizing nitrogen fertilizers, enhance micronutrients by using foliar fertilizer Poly Feed 19-19-19 to increase the resistance of plants.

Closely monitor the density of sucking pests, especially aphids to prevent timely. Proactively prevent aphids at the nursery stage, from the small plant to the flowering stage (because this is the stage that determines the rate of diseased plants and severe or mild disease). Currently, the most popular and effective product for sucking pests is Comda Gold 5WG, or Saimida 100SL (pay attention to spray a lot of water and do not mix many products and fertilizers to avoid harming the plants).

 

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To prevent, in addition to plowing and burying weed seeds, collecting weed stalks and stumps left after tilling the land to burn, not letting weeds produce seeds in production fields, etc., the use of chemical products is still a measure. optimal because of its ability to thoroughly kill weeds, reduce labor and take advantage of more time than manual weeding.To prepare for the coming Summer-Autumn rice crop, we would like to introduce to you a very new product of Saigon Plant Protection Joint Stock Company, which is Butoxim 5GR. This is a granular product used for spreading by Saigon Plant Protection Joint Stock Company in research, production and distribution.

 

 Miner has the scientific name Phyllocnistis citrella Staint., family Phyllocnistidae, order Lepidoptera. The  miner occurs in many countries in the tropics and subtropics. The main host of the miner is the citrus family - Rutaceae. In addition, the miner also attacks mangosteen and some other plants.

 

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.

 

Green bugs specialize in the fruit of citrus groups (oranges, tangerines, lemons, grapefruits, kumquats...), some people call them orange bugs, or orange suckers. Their scientific name is Rhynchocoris poseidon or Rhynchocoris humeralis.

 Spider mites are common pests on citrus trees, especially in hot and dry climates that are suitable for spiders to grow and cause severe damage.The group of harmful spiders is usually very small in size, unlike the natural enemy spiders.Spiders have a very short life cycle, high reproductive ability, create many generations in a year, so it is easy to break out into epidemics in a short time.

 

 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.

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.

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