Bacterial Root Cancer of Cherry Blossom and its Control measures

Bacterial root cancer is one of the most common root diseases in garden flower seedlings in northern China, which mostly occurs in alkaline soil areas. The disease not only harms cherry blossoms, but also harms Rosaceae plants such as elm and rose, as well as indoor and outdoor flowers and trees such as ginkgo and carnation. Its hosts cover more than 300 species of plants in 60 families.

Symptom

The disease often occurs in the root neck, especially at the graft interface of seedlings, and sometimes on lateral roots, branch roots or branches (vines).

Cancer is spherical at birth, can heal each other, the color is milky white or slightly reddish, as the tumor grows, the internal Lignification hardens, the epidermis cracked rough and gradually becomes brown to dark brown, the cancer can be as small as beans or as big as fists. Diseased seedlings have fewer fibrous roots, slow growth or yellow leaves, more withered branches, shorter florescence, and even death. The disease is so stubborn that even if the cancer is cleared, it can often be born again.

Pathogen and infection cycle

The disease is caused by Gram-negative Agrobacterium tumefaciens, which overwinters in the cortex or soil of cancer tissue and spreads through wounds caused by Rain Water, irrigation water, long-distance seedlings, human factors, worms or root-knot nematodes, etc., surviving in the range of 10 ℃ to 34 ℃, the optimum humidity is 22 ℃, less than 18 ℃ or higher than 30 ℃ is not easy to form nodules. Acid-alkali tolerance ranges from pH 5.7 to 9.2, which can cause disease within pH6.2 to 8. In the continuous cropping land with heavy alkali, the higher the humidity, the more serious the disease; in the loose sandy soil, the disease is less.

Prevention and cure measures

1. Strengthen quarantine for out-of-nursery or foreign seedlings, abandon diseased plants, find suspicious seedlings, soak the roots with 1% copper sulfate solution for 5 minutes and then immerse them in 2% lime water for 1 minute, or directly soak in streptomycin solution for 30 minutes for planting observation. 2. Apply carbofuran 3% granule according to 30 grams to 50 grams per square meter, turn the soil 15 cm to 20 cm, then pour water to kill root-knot nematodes and ground tigers and other pests; grafting should avoid wound contact with soil, grafting tools can be disinfected with 75% alcohol or 1% formaldehyde solution. 3. When a diseased plant is found, the tumor should be removed together with its surroundings, and the wound can be closed with Vaseline after disinfection with medical high iodine or streptomycin 400 international unit. Sulfur can be applied to the diseased plant at a time from 50g to 100g per square meter, and 20% Tuba wettable powder 500x solution or 14% Duoxiaoling water agent 150x solution can be injected around the diseased plant, and then once every semimonthly, a total of three or four times. 20 days after the resection of the tumor, 50% indada powder 100g to 150ppm solution can promote the root growth of the plant and rejuvenate the diseased plant. Other treatments were the same as before, and the effect of treatment was better before the root system entered vigorous growth in early spring or summer.