Recently, pear trees in Sun Yanjun, a farmer housekeeper in Pingdingshan City, Henan Province, suffered from this disease. On April 2, he sent a picture to an expert for consultation: "What is the reason for pear peeling and how is it formed?" Let's see what the experts say.
At the initial stage of trunk rot, cork is inclined to be oily.
Farmer housekeeper app expert answer:
Tamia Liu (Liaocheng City, Shandong Province-good at pear trees, grapes, jujube trees, etc. )
Symptoms of dry rot. Scrape the affected area and apply tebuconazole+humic acid foliar fertilizer.
Feng Tao (Lu 'an, Anhui-Good at Plant Protection Technology)
Dry rot. It is suggested that Keith Downing, octyl acetate, prochloraz manganese salt, calcium copper sulfate, bromothalonil, chloramine copper and clothianidin copper should be applied to prevent and treat rot.
Li Puxuan (Xi City, Shaanxi Province-good at planting pear trees, peach trees and apples).
Pear dry rot. Scrape off the focus and apply thiophanate acetate or Keith Downing to the wound.
Guo Xinhua (Liaocheng City, Shandong Province-Good at Plant Protection Technology)
Dry rot. Scrape off the rotten part, and apply chlorothalonil, Dofukang, ethylicin, octyl amine and Guokangbao to the affected part.
Nongguanjia knowledge Xiao classroom
Dry rot is a serious branch disease on pear trees, which is widespread in pear tree producing areas all over the country. It is a branch disease of pear trees, second only to rot.
Harmful symptoms
In the late stage of dry rot, spots and surface cracks appear.
In the later stage, the lesions were dehydrated, shriveled and sunken, and the cortex was split vertically and horizontally.
The diseased seedlings often have reddish-brown to dark-brown spots near the joint, which spread up and down the trunk, often forming concave stripes, and cracks appear at the joint between the diseased plants and the healthy plants. When the diseased spot surrounds the branches, the whole plant will die, and many slightly prominent black spots will be produced at the diseased site in the later stage.
At the early stage of the disease, moist and irregular purple spots appeared on the surface of the branches, and sauce-colored mucus flowed out. After the water in the injured part is lost, it becomes a sunken dark brown dry spot, resulting in many small black spots. The joint between the diseased part and the healthy part is cracked, and the diseased skin often bulges. In severe cases, the lesion surrounds the whole branch, resulting in the death of the whole branch. Sometimes the lesions only occur on one side of the big branches, forming concave withered spots.
The thick branches are damaged, and the initial lesions are light brown and moist, commonly known as "oil". Later, the embolus of the affected part cracked and tilted, showing the shape of "oil skin"; In the later stage, the lesions were dehydrated, shriveled and sunken, the cortex was cracked vertically and horizontally, and small black spots were raised under the skin. The lesions are grayish brown, irregular in shape and generally less harmful.
Weak branches of weak trees are damaged, and the diseased cortex will rot completely, and the diseased cortex will be necrotic and cracked, and the xylem will be exposed, resulting in the death of the upper part around the branches after one week. The damage of branchlets often leads to the formation of dense small black spots on dead branches, and gray mucus can overflow on the small black spots when wet.
Occurrence law
First, fertilizer. Too much and too late application of available nitrogen fertilizer leads to too fast growth and freezing.
Second, the wound. Dry rot is a higher fungal disease, and the pathogen overwinters on the diseased spots and diseased remains of branches with hyphae and conidia (small black spots). In humid environment, a large number of conidia (gray-white mucus) are produced and overflow on small black spots, and pathogen spores are mainly transmitted by wind and rain and infected from wounds. The diseases of weak trees and weak branches are serious, and young trees are vulnerable at the slow seedling stage, and the diseases are more serious in dry orchards and dry seasons. All factors that can lead to tree weakness will lead to or aggravate the disease.
Prevention and cure method
1, strengthen water and fertilizer management
Apply base fertilizer early and apply sufficient base fertilizer. The base fertilizer is mainly Xixing organic fertilizer and bio-organic fertilizer, and the amount of fertilization is appropriately adjusted according to the age, potential and crown size of the tree. Don't unilaterally apply nitrogen fertilizer, do a good job in orchard irrigation and drainage system, ensure enough water for trees to absorb and irrigate in time.
2, reasonable fruit hanging
The amount of fruit hanging depends on the tree potential, and the flowers and fruits should be thinned according to the age and the tree potential. Reduce the situation that trees are weak due to excessive fruit hanging and excessive tree consumption.
Step 3 remove the diseased spots
Strengthen orchard inspection in spring or when the fruit is close to maturity, and remove the diseased spots immediately if found to prevent the spread of infection.
4. Post-processing
Scrape off diseased spots, remove diseased branches and fruits, and take them out of the orchard for centralized burial or incineration.
Reference control agent
50% thiram wettable powder (moderately toxic) was applied with 50~ 100 times solution.
68%? Thiram wettable powder (low toxicity) uses 50~ 100 times solution.
70%? Flumeiling wettable powder (low toxicity) was applied with 50~ 100 times solution.
3% thiophanate-methyl paste (low toxicity) was applied to the diseased spot at a dosage of 200-300g/m2.
35% Propiconazole Carbendazim Suspension Emulsion (slightly toxic) was applied with 600-800 times of foam scar and spray.
1.6% thiamethoxam daub (low toxicity) with 80- 1.20g/m2.
3.3 15% methylthionaphthylacetic acid liniment (low toxicity) was applied to the lesion scar with the original solution.
Apply 1.9% octylamine acetate aqueous solution (low toxicity) to the wound with 50- 100 times solution.
Apply 5% copper lotion (low toxicity) to the scar, 95ml/m2.
Use 2. 12% copper humate aqueous solution (low toxicity) 200ml/m2 to smear the scar.
Apply 4.5% humic acid copper sulfate aqueous solution (low toxicity) to the diseased scar, and the dosage is 200-300ml/m2.
Use 100-200 times solution to smear 45% amobam aqua (low toxicity).
Knowledge expansion
Pear rot and dry rot are two serious fungal diseases on pear trees, and the incidence rate of diseased plants in damaged pear orchards can reach 50%-80%. Although the pathogenesis and preventive measures of these two diseases are basically the same, their symptoms are different, and the differences are as follows:
Pear rot mainly occurs on main branches and lateral branches, less on branchlets and trunk, and easily occurs on sunny sides and branches of big branches. At the early stage of the disease, the diseased spots were waterlogged and slightly raised, the subcutaneous cortex of the disease rotted (with the smell of distiller's grains) and turned brown, the diseased part gradually lost water, and there were cracks at the junction between the diseased part and the healthy part. Finally, small black spots grew on the surface of the affected area. In winter, the diseased skin stands up, and in severe cases, branches or whole trees die.
The incidence of pear dry rot is mainly in trunk and branches, and seedlings and young trees are also prone to disease. At the beginning of the disease, dark brown spots appeared on the branches, which were hard, slightly wet and rotten to the xylem. In the later stage, the affected part lost water, sagged, cracked all around, and the surface was covered with small black spots.
Finally, how to make planting management easier? Tip: download the farmer housekeeper APP (please look for the ladybug logo), and the latest agricultural management will be updated every day in the "Agricultural Science and Technology" column to help you find the right direction and learn scientific management. In addition, in the "Q&A" column, there are many experts online to help you solve problems, and easy management is no longer an empty talk!