Punjab Agricultural University - Advisory on protecting crops from heat

June 26, 2009 Ludhiana

The persistent hot and dry weather for the past couple of weeks is not just killing for humans but for crops too. Except for paddy, all other kharif crops like sugarcane, cotton, sunflower, moong, mash, vegetable and fruit crops are badly affected by scorching heat.

According to cotton experts of Punjab Agricultural University, excessive heat has a deteriorating effect on cotton plants. A yellow ring develops around the stem that is susceptible to bacteria and other disease pathogens which attack the plant. As a result which, the stem wilts and plant dies.

The hot temperature of June is unbearable for fruit crops also, specially for newly planted fruit trees, which require adequate protection. According to horticulture experts of university, the tree trunks directly exposed to intensive sun rays from south-western side often cause sun-burn bush injuries to fruit plant. Since the evaporation losses are high due to dry weather, the tree trunks loose moisture. The develops cracks and sometimes peels off completely exposing the inner sensitive largers. At times such damage eventually cause death of the plant or severe damage to some part. The fruit trees of mango, litchi, citrus, guava and papaya are comparatively more prone to damage from hot weather.

The PAU scientists have advised the farmers to take suitable precautions to save fruit plant from heat. They have advised painting the lower tree trunks with white wash solution. The white wash can be prepared by dissolving 25 kg. slaked lime, 500 gm copper sulphate and 500 gm of gum suresh in 100 litres of water. Also, giving frequent irrigation at regular intervals is helpful in checking the heat stress. Young fruit plants which are tender, should be protected from heat by erecting thaches or kullies made of sarkanda, parali or date palm leaves.

Vegetable like chilli, okra and cucurbits i.e. bittergourd, bottlegourd which are in the field are also affected by heat. The high temperature affects the fruit setting ability in these vegetables. Reports have been received from the farmers of flower drop and fruit drop in these crops. This is happening due to the abnormal temperature which interfere with the pollination process and thus the fruit setting is not taking place. The farmers therefore, are advised to provide light but frequent irrigations to create the cool climate to some extent.

Some sun-burn injuries have also been observed in bittergourd crop specially which has been grown on trellis/trained structures. This is not a disease, but it is high temperature injury. The farmers who are doing net-house cultivation should use this high temperature for killing the soil borne disease organisms and nematodes by turning over/ cultivating the soil in the net house. This can also be covered with the polythene sheets to further increase the soil temperature.

(Source: PAU Ludhiana)