Shot Hole and Brown Rot in Hunza-Nagar
By Zulfiqar Ali Ghazi
Shot hole disease, which may also be known as Coryneum blight, is a serious issue in many fruit trees. It is most commonly seen in peach, apricot, and plum trees but may also affect almond and prune trees. Some flowering ornamental trees can be affected as well. Since little can be done to control shot hole fungus once the trees have been infected, prevention is essential in treating shot hole disease.
Shot hole disease thrives in wet conditions, especially during extended wet periods. The disease is most noticeable in spring, as new growth is most susceptible. Shot hole fungus commonly grows over winter inside the infected buds, as well as twig lesions, where the spores may thrive for several months. Therefore, it is important to thoroughly inspect trees after leaf fall for any symptoms.
Most signs of shot hole disease occur in spring, causing spots (or lesions) on new buds and young leaves and shoots. Buds will have a varnished appearance and spots will first look reddish or purplish-brown in color and about ¼ inch in diameter. Eventually, these spots become larger, turning brown and falling out—giving the appearance of ‘gunshot holes’ in the foliage. As it progresses, the leaves will drop. The stress also affects the tree’s ability to produce, and any fruit that may develop will usually be affected as well with spotting on the upper surface that may even become rough.
Shot Hole is most prevalent in the years with wet spring. The optimal conditions for infection are during tree dormancy in winters when there is free water for at least 24 hours and temperature above 2.5 degree. When these conditions occur, the fungus (spores) requires as little as 6 hours to infect twigs and buds.
Frequent inspections are required to identify the problem before outburst especially in a year with wet conditions from flowing to the ripening of the fruit. This year Gilgit-Baltistan has wet spring and worm summer, temperature elevates suddenly and abnormally which provides optimal conditions to short hole to outburst especially in Central Hunza and SAS valley. The conditions in other valleys may be same as Hunza- Nagar, but no data is available to point out the problem with certainty.
In central Hunza and in SAS valley, the conditions are very much poor in the lower areas while in higher areas is towards the mountain sides on the slops is satisfactory. This condition may ultimately give a great sat back to the farmers who earn from dried apricots. The quality of dried apricots will be poor this year due to the disease. I will appreciate if someone come with suggestions to control at this stage.