Pruning, watering, mulching key to protect fruit trees from heat

In Punjab, the months of May and June bring intense sunlight and high temperatures. During this period, the weather becomes extremely hot with strong winds, which adversely affect fruit trees. The sharp rays of the sun damage fruits, leaves, branches and trunks, often leading to decay.

This intense heat particularly affects mango, litchi, lemon, pomegranate and papaya plants more severely than other fruit trees. Lemon leaves suffer from scorching, along with the development of white to brown spots, which eventually lead to drying and leaf fall. Similarly, fruits on trees are damaged by the sun, causing cracking, especially in lemon, litchi and mango during hot and dry weather, resulting in reduced yield and quality.

“To protect fruit trees from the harmful effects of summer, orchardists must adopt a few essential measures. During hot summers, water management plays a crucial role in protecting trees from heat stress. Watering helps reduce soil temperature around the roots and canopy, thereby lowering the chances of fruit cracking. Spraying water on fruit trees during extreme heat can also minimise the adverse effects of high temperatures. Newly planted citrus fruit saplings (3-4 years old) should be watered weekly during summer as the fruit develops in April. The hot weather increases the risk of fruit drop and cracking,” said Dr Yamini Sharma, Fruit Scientist at Punjab Agricultural University’s Regional Station.

Young saplings should be covered using straw, dried grass, or bamboo structures to shield them from direct sunlight. Before establishing an orchard, windbreak trees should be planted around the periphery. These trees must be fully grown before the fruit trees are planted. Windbreak species such as eucalyptus, mango, jamun, arjun, bael, tahli, and mulberry should be planted particularly on the southern and western sides. Between these trees, other plants like galgal (wild lemon), jatti-khatti, karonda and bougainvillea may be grown for additional protection. However, lemon orchards should not be surrounded by other lemon trees as a windbreak. These windbreak trees help reduce damage caused by strong winds and storms, added Sukhjit Kaur, another expert from PAU.

Applying whitewash to the trunks of fruit trees protects them from direct sun exposure. The white colour reflects sunlight, preventing excessive heat absorption. Additionally, whitewashing eliminates harmful pests and insects on the trunks. Mixing copper sulphate (blue vitriol) with the whitewash helps protect trees from fungal infections. Whitewashing should be done in April or May and reapplied in June or July, said Rajinder Singh Bal.

To retain moisture in orchards, a thin covering layer (such as plastic sheets or straw) should be spread under the base of fruit-bearing trees. This helps maintain cooler soil temperatures and shields the trees from excessive heat. The covering layer can be organic (straw, sugarcane residue, or dry grass) or inorganic (plastic mulching sheet).

It has been observed that shorter trees withstand intense sunlight better than taller ones. Therefore, in hot and dry regions, fruit trees should be pruned to maintain a lower height. Shorter trees are also less affected by strong winds. It has also been noted that fruits on taller litchi trees crack more than those on shorter trees due to increased sun exposure. Pruning helps maintain an optimal tree height, thereby reducing fruit cracking, added Dr Bal.

Ludhiana