Peach Tree Rot: Control Methods and Key Technical Points

Peach tree rot, also known as dieback disease, causes branches to wither and die after the peach tree is affected, forming canker lesions on large branches and the trunk; if not treated in time, it quickly causes the entire tree to die. The main causes of this disease are: freeze damage and extensive management; improper fertilization and years with heavy autumn rain, which delay peach tree dormancy and reduce the tree's cold resistance. The specific control methods are as follows:

Strengthen the tree to prevent disease

① Reasonable load: Determine the appropriate fruit load based on the tree's growth condition and fertilization level.

② Increase fertilizer and water: Pay attention to increasing organic fertilizer, phosphorus, potassium, and trace element fertilizers, while not applying excessive nitrogen fertilizer.

③ Protect leaves and promote roots: Early leaf drop is an important cause of weakening tree vigor, so timely control of pests and diseases that cause early leaf drop in peach trees is necessary.

Pay attention to tree protection

① Avoid freeze damage and sunscald: Peach tree branches facing the sun experience large day-night temperature differences and are prone to freeze damage in winter; in summer, the sunny side has no leaf cover and is prone to bark death from sun exposure. Effective measures for preventing freeze damage include: first, whitewashing the trunk to reduce the day-night temperature difference; second, tying straw around the trunk to prevent freezing. A commonly used whitewash formula is 12-13 kg of quicklime, plus 2 kg of lime sulfur concentrate (about 20 degrees Baume), plus 2 kg of salt, plus 36 kg of clean water. Whitewashing can also prevent sunscald on branches.

② Protect wounds: Larger saw cuts should be smoothed flat and then coated with varnish or thiophanate ointment, S-921 antibacterial agent, etc. for protection. After larger lesions are cured, bridge grafting should be performed in time and protected.

Timely treatment of lesions

① Scrape the bark: Peach tree rot generally damages the shallow layer of bark. Before peach trees bud, scraping off the raised bark and necrotic tissue can remove most lesions and most of the pathogens carried on the tree; at the same time, scraping the bark stimulates the tree to produce callus tissue and promotes lesion healing. After scraping off the diseased tissue, apply a mixture of 1 part 70% thiophanate-methyl wettable powder plus 2.5 parts vegetable oil to the diseased area, which has a good effect on curing lesions; you can also apply S-921 antibiotic at 20-30 times dilution, 843 rehabilitation agent concentrate, etc., to prevent recurrence of the disease scars.

② Use RBF fruit tree protective film agent for control: RBF fruit tree protective film agent (Guokangbao) is a high-tech product developed by the Shanxi Academy of Agricultural Sciences Pomology Institute and is currently the newest specific agent for controlling peach rot in China. It can be applied to the trunk or sprayed over the entire canopy and has the dual function of sterilization and tree protection. According to efficacy trials, the effective rate for curing peach tree rot reaches 94%, the incidence rate is controlled below 5%, and the recurrence rate of disease scars does not exceed 3%. In addition, applying the solution to treat disease scars can stimulate new bark growth, restore tree vigor as quickly as possible, and increase peach tree yield.

The control method is: spray the entire canopy once each before spring bud break and after leaf fall with a 150-200 times dilution of the solution, which can effectively control peach tree rot, and can also reduce tree water evaporation, inhibit shoot dieback, and improve the tree's cold and drought resistance; in spring, brush the peach tree trunk with a 50-60 times dilution (instead of lime sulfur), which can seal and suffocate overwintering parasitic eggs in the crevices of the trunk and main branches, reducing pest occurrence; in spring, after scraping and treating peach tree rot, apply a 5-10 times dilution to the disease scars to promote healing.