Experts advise managing cotton at boll formation

Manav Mander

Ludhiana, July 29

The numerous varieties and hybrids of cotton enter the process of flowering and fruiting from early July to late September. During this period, the number of bolls formed per plant directly influence the cotton seed yield. Therefore, during this period, farmers should prioritise water, nutrient and pest management to safeguard plant health, allowing for successful pollination and fruit set, ultimately, ensuring maximum yield and quality of cotton fibre.

To this end, experts from Punjab Agricultural University’s Farm Advisory Service Centre (FASC) shared insights on managing the crop.

FASC’s Navneet Kaur said that cotton crop can neither tolerate excessive irrigation nor drought-like conditions. “Sometimes, in August, heavy and prolonged rains lead to unwanted plant growth, particularly in heavy textured soil. Due to excessive growth, the lower parts of the plants do not get the required amount of sunlight, which results in shedding of flower buds. Excess moisture sometimes causes rotting of early fruiting bolls. In such a situation, efforts should be made to drain the excess water from the fields,” she added.

Talking about fertilizer management, Amarjeet Singh Sandhu said, to ensure higher yield, the crop should be sprayed on four times with two per cent potassium nitrate solution once a week from the beginning of flowering.

To prepare the potassium nitrate solution for an acre, dissolve two kg of potassium nitrate in 100 liters of water.

When the plant is full of flowers, sometimes the leaves of the plant turn red due to deficiency of magnesium. To avoid this, the crop must be sprayed with one per cent magnesium sulphate — after dissolving one kg of magnesium sulphate in 100 liters of water — at an interval of 15 days during flowering.

Pest, disease prevention

Whitefly: Whitefly nymphs are too small to be visible to the naked eye. Consequently, the population of whitefly sometimes seems to have been controlled after the initial spraying, but after a few days, these nymphs start damaging the crop as adults. Therefore, it is crucial to spray the crop after three-four days to completely eradicate the whitefly population.

Pink bollworm: The appearance of deformed flower buds in cotton field indicates that pink bollworm larvae have entered the field. The signs of presence of pink bollworn larvae are not visible externally on the bolls. However, the larvae are damaging the bolls from the inside. “Farmers are advised to be vigilant and examine their fields at least twice-a-week to ensure the bollworm does not damage more than five per cent of the freshly shed fruiting bodies (squares, buds and young bolls). To monitor, randomly collect 20 bolls from the field. If larvae are found, spray the crop with recommended insecticides,” said Pritpal Singh, another expert from FASC.

Leaf curl: Leaf curl is a viral disease which is transmitted by whitefly. The number of flowers and fruiting bodies are reduced, which leads to reduced yield. The disease can be controlled by uprooting the affected plants from time to time and managing whitefly populations.

Bacterial blight: It spreads through seeds. The diseased plants start developing water-soaked spots on either side of the leaf, which turn brown to black. The bacterium also infects the young developing bolls and causes small, round, water-soaked spots to appear at the centre. Use disease-free seed to avoid blight.

Leaf spot disease: Leaf spots are caused by fungi that spread through spores. The infestation causes yellow to brown spots on the leaves. If humid weather prevails for long, spray the crop with Amistar Top 325 SC (azoxystrobin difenoconazole) at 200 ml per acre in 200 liters of water.