Faisalabad:The agriculture experts advised potato growers to adopt recommended cultivation, irrigation, pest-control and harvesting practices to improve yield, protect the crop from diseases and secure better returns from the important cash crop particularly during the ongoing autumn sowing season.
A spokesman for the Agriculture (Extension) Department said here on Monday that potato is an important crop in Pakistan because of its comparatively higher per-acre income and nutritional value. It contains substantial quantities of starch, vitamins, minerals and proteins. It is also considered an important component of the food supply, he added.
He said that two potato crops – spring and autumn – were grown in the plains of Punjab while October was the most suitable period for sowing the autumn crop.
He said that early sowing could result in poor germination because of high temperatures and increase the risk of rotting of seed tubers and mite attacks. Therefore, the growers should sow the crop when temperatures remained between 28 and 32 degrees Celsius and harvest it during January and February, he added.
He said that for seed production, the farmers should complete sowing by first fortnight of October and cutting the vines by the first week of January to protect the crop from virus-transmitting insects and allow the potato skin to harden. The crop should be harvested within seven to 10 days after vine cutting, he added.
He said that the farmers should avoid from using freshly harvested potatoes as seed for a new crop. Breaking dormancy before planting was imperative while potatoes generally came out of dormancy naturally after being stored for 10 to 12 weeks.
He recommended using 1200 to 1500 kilograms per acre healthy, disease-free and certified seed and said that the seed removed from cold storage should be taken out around 10 days before planting and spread in a shaded place so that it could gradually adjust to outside temperatures and develop sprouts. The growers should also use the approved potato varieties for cultivation, he added.
He said that for potato cultivation, fertile loamy soil with good drainage and adequate organic matter was recommended. The land should be prepared by using a mould board plough once followed by three to four ploughings with an ordinary plough to make the soil soft and friable. Proper land leveling was also stressed to prevent waterlogging and ensure uniform germination, he added.
He advised the farmers to conduct soil analysis before determining fertilizer requirements. In the absence of soil testing, an average-fertility field could receive 100 kg nitrogen, 50 kg phosphorus, 50kg potash and 10 kg zinc sulphate (21 percent) per acre.
Where farmyard manure was applied, additional micronutrients would not generally be required. Otherwise, depending on soil conditions, the growers could apply 30 kg ferrous sulphate, 12 kg manganese sulphate and 2kg boric acid per acre, he added.
He said that all phosphorus, potash, zinc and other micronutrient fertilizers should be applied at planting while half of the nitrogen fertilizer should be applied at sowing and the remaining half one month later along with irrigation.
He said that potatoes should be planted on ridges with a spacing of 75 centimeters between ridges and 20 centimeters between plants. The seed should generally be placed seven to 10 centimeters deep, although the depth could be increased up to 15 centimeters where planting was carried out with a ridging plough. For seed production, a plant-to-plant distance of 15 centimeters was recommended to obtain smaller tubers suitable for seed purposes, he added.
Regarding irrigation, he advised the growers to give the first irrigation immediately after planting, ensuring that water did not rise over the ridges and reached only about two-thirds of their height.
He said that excessive water could harden the soil and adversely affect germination. Subsequent irrigation intervals could be extended to 10 to 15 days depending on weather conditions, while irrigation should be stopped 15 days before harvesting.
For weed control, the farmers should use herbicides only after consulting local field staff of the Agriculture Extension and Pest Warning Department, he added.
He identified late blight, early blight, dry rot or wilt, common scab, mycoplasma, potato leaf roll virus, potato virus Y and mosaic among the diseases that could severely affect the crop and reduce production.
He recommended the use of healthy, disease-free seed, cultivation of resistant varieties and timely weed control as key preventive measures.
He said that several harmful insects including cutworms, jassids, aphids, whiteflies, potato tuber moth, American bollworm and armyworm could also attack potato plants and damage leaves and other plant parts.
He said that the farmers should install light traps, carry out hoeing followed by irrigation and control weeds as part of an integrated pest-management approach.
In case of severe pest or disease infestation, the growers should consult Agriculture Extension and Pest Warning field staff before applying recommended new-chemistry pesticides, he added.
He also stressed the need of proper harvesting and post-harvest handling to minimize losses.
He said that potato vines should be cut 10 to 15 days before harvesting to harden the skin of the tubers, helping prevent rotting during cold storage. Harvesting should preferably be carried out in the morning when temperatures were relatively lower.
After harvesting, potatoes should be kept in a shaded place for three to four days to allow wounds caused during harvesting to heal, he added.
He further cautioned the farmers against storing harvested autumn potatoes in large heaps without adequate ventilation. Since the crop is generally harvested in January and February, when market prices may be relatively low, growers sometimes keep potatoes in heaps on farms in anticipation of better prices. However, poor air circulation can cause rotting, while excessive heat can damage their appearance and reduce their market value, he added.
For improved on-farm storage, he recommended constructing potato heaps on beds at least one foot above ground level and installing ducts to facilitate air circulation inside the heap. The ducts should be closed in the morning to prevent hot air from entering and opened at night to allow cool air to circulate, he added.
He said that a chimney should also be installed to release accumulated heat while an appropriate layer of straw should be placed over the heap to protect the potatoes from weather fluctuations.
Adoption of these improved storage practices could enable growers to keep potatoes on the farm for a longer period while maintaining their quality and market value, he added.