Clever Prevention of Potato Ring Rot

Potato ring rot is a common disease, but because the symptoms of infected seed potatoes, especially the external symptoms, are not obvious, infection readily occurs during seed cutting and storage. In production it often causes four situations: (1) seed rot during sprouting. (2) failure to emerge after sowing. (3) death of seedlings after emergence. (4) formation of diseased plants, few tubers set, small tubers, and rotting of seed potatoes (in sharp contrast to normal seed potatoes, whose tuber shape remains intact into the late growth stage). According to a survey of diseased fields in Zouping County, yield reductions reached 30%-80%.

The pathogen is a bacterium with a short survival period in soil. It mainly overwinters in the tubers, and the transmission route is infected seed potatoes, so pre-sowing prevention yields twice the result with half the effort. Preventive measures:

1. Strict management of seed potatoes (1) Seed potato @#@136@#@ departments should remove diseased potatoes while harvesting during self-propagation; during transport and transfer, quarantine must be strengthened, and transferring seed from diseased areas is strictly prohibited. (2) After the tubers are harvested, first spread them in a ventilated place for 2-3 weeks, and store them in a cellar when the temperature is stable at 0°C. Before storage, strictly re-select the seed potatoes and remove diseased and rotten tubers and tubers that are mechanically damaged, insect-damaged, flood-affected, or cold-injured. (3) For storage, choose a wind-sheltered, sunny place with good drainage. During storage, ensure ventilation and air permeability, maintain the temperature at 1-3°C and the relative humidity at about 90%, check frequently, and promptly remove diseased tubers together with the surrounding tubers.

2. Select disease-resistant varieties suitable for local planting, such as Luyin No. 1 (Holland No. 7), Zhengshu No. 4, etc.

3. Sowing whole small potatoes Whole small potatoes have strong vitality and good disease resistance, and at the same time can avoid cross-infection by ring rot bacteria and other pathogens, as well as avoid poor healing of cut surfaces and invasion by saprophytic bacteria. In production, giving priority to whole small potatoes as seed potatoes is advocated.

4. Sprout whole potatoes, cut just before sowing This method mainly avoids long-term contact between cut surfaces. Strictly remove diseased potatoes before sprouting; before cutting, prepare as many cutting knives as possible, and first disinfect the knives with alcohol or flame; observe the cut surface when cutting potatoes, and if the vascular bundles on the cut surface are found to have turned milky yellow to dark brown, first remove the diseased potatoes, then change the knife, and soak the previously used knife in a 50 mg/L copper sulfate solution for more than 10 minutes.

5. Mixing seed with plant ash Sprinkle a layer of plant ash on the cut surface, which both keeps the cut surface dry and prevents pathogens, and also adds potassium fertilizer, helping drought resistance and cold resistance.

6. Applying chemicals in the holes Apply 50 g of 50 mg/kg copper sulfate poisoned soil per hole, taking care to spread it evenly around.

7. Formula fertilization, ridge cultivation Increase the application of organic fertilizer, with a suitable ratio of nitrogen, phosphorus, and potassium of about 2.5:7:4.5; apply calcium superphosphate as the phosphorus fertilizer to supplement calcium; plant on ridges to enhance the disease resistance of the plants.