Common problems in potato production and their solutions

Zhaosu is located in the northwest border region, at an altitude of 1720-1860 m, with a short frost-free period and a cool mountainous climate. With the adjustment of the industrial structure, potato has become the main crop of our regiment.

1. Existing problems

1. Climatic effects

From April to early May 2007, due to high temperatures and dry soil, potato emergence was difficult and seed potatoes shriveled. After emergence, there was abundant rain, causing seed rot and missing plants with gaps in the rows.

2. Poor quality of seed potatoes

In 2007, seed potatoes suffered from rot, disease and damage. When cutting seed potatoes, diseased tubers were not strictly removed. At the same time, virus-carrying tuber pieces were transmitted into the soil through contamination by the cutting knife, causing seed rot and missing plants and increasing the disease incidence in the field. Planting bacteria-carrying seed potatoes led to the spread of pathogens.

3. Effects of nitrogen fertilizer

During the growth of potatoes, excessive application of nitrogen fertilizer caused the upper stems and leaves of the plants to grow luxuriantly, while the lower leaves were deprived of sunlight and rotted, resulting in top-heavy plants and severe lodging, which led to delayed tuber formation and low starch content and yield.

4. Improper management

Poor tillage quality and too deep or too shallow sowing both affect the field emergence rate. Improper chemical weed control left many weeds in the field, and tuber growth was inhibited, thereby affecting potato yield. Tillage machinery was not matched, and intertillage and hilling were not timely, so the underground growth and development environment for potato tubers could not be satisfied. Tubers easily pushed out of the soil surface and formed green heads after exposure to light. Late blight pathogens easily seeped into the potato field with rainwater, increasing the infection rate of tubers and reducing yield.

5. Too sparse sowing

Cutting seed potatoes too early and improper storage caused seed rot and shriveling at sowing. Sowing was relatively late, potato sprouts were long, and mechanical damage caused missing plants in the field. Intertillage and weeding were not timely, weeds grew vigorously, and weeds suppressed the seedlings. Frost occurred in mid-May, causing some potato seedlings to freeze to death.

6. Effects of diseases

Late blight occurs relatively commonly and severely in the Zhaosu reclamation area. This is mainly because lightly late-blight-infected tubers were planted into the soil at sowing. When continuous rainy weather occurred, with humidity above 75% and temperature above 10°C, lesions appeared on the leaves. The sporangia produced by diseased leaves spread in all directions with wind, rain and airflow, fell into the soil and infected the growing tubers.

2. Solutions

1. Seed potato quality

Select high-quality seed potatoes, remove tubers with necrotic eyes and those that are rotten, diseased or damaged, and choose healthy seed potatoes with regular tuber shape, smooth skin, a tuber weight of 20-25 g and 1-2 bud eyes as seed. Seed potatoes weighing less than 40 g can be planted whole. Larger tubers are conducive to emergence and enhance drought resistance. It is strictly forbidden to plant rotten and virus-carrying tuber pieces into the soil.

Cut the seed potatoes 2-3 days before sowing and remove diseased tubers. Prepare two cutting knives, strictly disinfect them with 75% alcohol or 0.1%-0.2% potassium permanganate solution, and use them alternately to prevent disease transmission. If the tuber flesh changes color, it can be discarded. After cutting, store the pieces in a well-ventilated place to prevent rot. Fresh plant ash can also be used to dress the seed so that the cut surfaces are evenly coated with plant ash. The skin of seed potatoes often carries pathogens, so 70% thiophanate-methyl + agricultural streptomycin can be used for seed dressing as a surface treatment, which has a good control effect on potato early blight and late blight.

2. Seed potato transport and transfer

15 days before sowing, move the seed potatoes from the seed cellar to the outdoors to dry in the sun and break dormancy. Keeping the tuber surface dry can inhibit the breeding and spread of pathogens and prevent seed rot after rain. Promote sprouting before sowing to promote early maturity and increase yield. During the sprouting process, eliminate diseased and rotten potatoes to reduce the rate of diseased plants or missing plants and gaps in the field after sowing, which is conducive to full stands and strong seedlings.

3. Crop rotation

Potato is most averse to continuous cropping, so rotation should be practiced. The previous crop should preferably be wheat, corn and other crops, which can reduce disease pressure to a minimum and also help eliminate weeds. It is best not to use Solanaceae crops as the previous crop.

4. Sowing method

Sow when the 10 cm soil temperature is stable at 7-8°C. The suitable sowing period in the Zhaosu area is from the end of April to the beginning of May. According to different models of seeders, adjust the plant and row spacing appropriately, with a plant spacing of 15-20 cm and a row spacing of 80 cm being suitable. According to soil moisture, the sowing depth is 8-12 cm, with 4200-4500 plants retained per 667 sq m and a sowing rate of 200-220 kg.

5. Fertilizer types

To produce 1000 kg of potatoes, 3.5 kg of pure nitrogen, 1.5-2 kg of pure phosphorus and 8-10 kg of pure potassium are required. Apply chemical fertilizer deeply before sowing to avoid contact between fertilizer and seed. Apply 10-15 kg of diammonium phosphate, 2.5-5 kg of urea and 15 kg of potassium sulfate per 667 sq m.

6. Field management

① After sowing and before potato seedlings emerge, use non-selective herbicides such as Nongminle or Henaisi to control weeds. For potato fields mainly infested with grassy weeds, use 35-40 mL of 10.8% haloxyfop-R-methyl emulsifiable concentrate or 70-90 mL of quizalofop-p-tefuryl per 667 sq m and spray evenly with water. In plots with many broadleaf weeds, use 150-200 g of bentazone per 667 sq m and spray evenly with water.

② After the potato seedlings show rows, use an intertillage and hilling machine for the first intertillage and hilling to raise soil temperature and promote growth, with a tillage depth of 8-10 cm, and combine it with weed control. When the seedlings are 15-20 cm tall, use the intertillage and hilling machine for a second hilling to thicken and widen the ridge platform, provide good conditions for tuber expansion, and reduce rotten potatoes and green heads. In the early stage of tuber formation, to prevent excessive vegetative growth, spray 50 g of paclobutrazol or 200 g of chlormequat per 667 sq m, mixed with foliar fertilizer, to promote tuber expansion and increase yield.

7. Pest and disease control

Common potato diseases include early blight, late blight, ring rot and black leg. Late blight mostly occurs in seasons with more rain and around the flowering stage of the plants. Control it early with mancozeb or fluopicolide-propamocarb, propineb and others. If potato aphids or 28-spotted ladybird beetles are found, monocrotophos, thiodicarb and deltamethrin can be selected for alternating use. In addition, according to growth conditions, spray 1% potassium dihydrogen phosphate and 1% urea solution on the leaves to improve plant disease resistance and prolong the functional period of the leaves. For severely affected plots, control continuously. The interval between pesticide applications is 7-10 days. The disease period of potatoes in the Zhaosu reclamation area is generally from mid-June to mid-August, when early and late blight occur alternately and should be prevented together. During the growth period, control should be carried out no fewer than 3-4 times.