Whitefly attack on cotton crop feared

MULTAN: Low temperature plays a key role in increasing the growth rate of pests against cotton crop as the pests thrive in hot and dry climate.

The human blunders of burning fossil fuels such as oil gas and coal heating the planet and changing the climate provide an ample environment for pests to thrive and destroy the crops, scientists, and experts said. The Meteorological Office has predicted the temperature will range between 28-38 centigrade in the current month in cotton belt districts of Punjab, particularly in South Punjab which contributes a lion’s share in cotton production.

Similarly, the humidity level will fluctuate during the month. The current month’s temperature data shows the most favouring for whitefly growth. Temperature has a significant impact on the survival and life cycle of whiteflies. The weather metre interprets minimum and maximum temperatures from 26 degrees to 40 degrees in the current month from September 10 at 39 degrees to 40 degrees on September 14. The temperature is not expected to increase from 38 degrees for the rest of the month. September is considered the month of whiteflies where the whiteflies thrive in hot, dry climates with temperatures between 35-42 centigrades and relative humidity below 50pc.

However, whitefly survival rates on cotton are intermediate, ranging from 37-64pc between 20-32 degrees. Whiteflies are a major pest for cotton crops and can cause significant damage. Whiteflies are most comfortable in temperatures between 20 and 30 centrages, depending on the species. The flying pest has six development stages, including the egg stage, four larvae stages (including pupa), and the adult insect. The greenhouse whitefly tends to spread over the plant vertically, considering that the larvae can only move in the first stage. Adult insects prefer to lay their eggs on young leaves well inside the plant, and this is where you tend to find the eggs and young larvae of greenhouse whiteflies. The whitefly invasion affected 50pc crops and caused damage to the crop last year, reducing boll size and production.

The total life cycle ranges from 14 to 107 days, depending upon the weather conditions. There are about 12 overlapping generations in a year and the pest also reproduces parthenogenetically at times.

Whiteflies have a wide host range. The damage from whitefly is uncountable and the pest not only reduces production but it also deteriorates fibre quality. The symptoms of a whitefly attack include chlorotic spots on the leaves and upward curling of leaves. Leaves become reddish and brittle. Premature leaf dropping, boll bursting and poor quality lint due to honeydew secretion. The pests use their piercing, needlelike mouthparts to suck sap from phloem, the food-conducting tissues in plant stems and leaves.

Large populations can cause leaves to turn yellow, appear dry, or fall off plants. Like aphids, whiteflies excrete a sugary liquid called honeydew, so leaves may be sticky or covered with black sooty mould that grows on the honeydew. The honeydew attracts ants, which interfere with the activities of natural enemies that may control whiteflies and other pests. Farm experts have suggested whitefly management can minimise the threats of attack.

They suggested growers avoid alternately cultivating host crops of the whitefly like brinjal, bhindi, tomato, tobacco and sunflower in the vicinity of the cotton crop. Spraying fermented cow milk on crops can reduce whitefly populations by up to 60pc. The casein protein in milk sticks to the wings of whiteflies and kills them.

Meanwhile, the Punjab Agriculture Secretary, Iftikhar Ali Sahu, chaired a review meeting in Multan about the current situation of cotton and the impact of recent rains on the crop. He emphasised the need for accelerated field activities to guide cotton farmers and ensure better care for the crop. Sahu also highlighted the importance of issuing timely advisories to protect the cotton crop from pests and diseases based on the weather forecast. He said the involvement of young agricultural graduates in practical activities is part of the Chief Minister Punjab internship programme starting from September 16.

Additional Secretary Task Force Punjab Rana Shabbir Ahmed Khan, Director General Agriculture Extension Punjab Chaudhry Abdul Hameed, Director General Agriculture Pest Warning Dr Amir Rasool, Director General Agricultural Information Punjab Naveed Ismat Kahlon, Director General Crop Reporting Service Abdul Qayyum, Chief Scientist Ayub Research Dr Sajidur Rahman, Focal Person Cotton Dr Muhammad Anjum Ali, Progressive Cotton Grower Syed Hasan Raza, Khalid Mahmood Khokhar, Cotton Expert Dr Muhammad Iqbal Bandisha and others attended the meeting.