Control Methods for Phomopsis Leaf Spot of Pineapple
Phomopsis leaf spot of pineapple is a common disease, belonging to one type of leaf spot disease, mainly affecting the leaves, impacting photosynthesis in the leaves, and causing the fruit tree to be unable to grow and develop normally.
Symptoms Phomopsis leaf spot affects the middle part of the leaf; the initial lesions are elongated-round or irregular in shape, flat, with light yellow edges and a honey-yellow center. Embedded beneath the epidermis in the center of the lesions are small black dots; these are the fungal pycnidia.
Pathogen The pathogen of Phomopsis leaf spot is Phomopsis ananassae Xiang et P.K. Chi. The pycnidia are dot-like, solitary or coalescent, embedded beneath the epidermis, dark brown, spherical or irregular in shape. Type A conidia are colorless, single-celled, spindle-shaped or elliptical, with two oil droplets; Type B conidia are colorless, single-celled, thread-like, and curved.
Occurrence characteristics The pathogen mainly overwinters on diseased leaves in the form of mycelium. In the following year, when conditions are suitable, the pathogen produces large numbers of conidia, which are mainly spread by wind and rain and by insects. The pathogen has weak parasitic ability and invades through wounds. In the cultivation and management of fruit trees, orchards with extensive management and weaker tree vigor are prone to the disease. This disease favors high-humidity environments, so attention should be paid to this during control.
Control methods
(1) Strengthen orchard management. Fertilize and irrigate reasonably to enhance tree vigor and improve the tree's disease resistance. Prune scientifically, cut off dead branches and diseased leaves, regulate ventilation and light penetration, pay attention to drainage measures, reduce orchard humidity, and maintain appropriate temperature and humidity in the orchard. In conjunction with pruning, clean up the orchard, promptly remove diseased leaves and dead branches and fallen leaves, and reduce sources of inoculum.
(2) Chemical control. When necessary, pesticide spraying can be carried out; the available agents are 50% carbendazim wettable powder at 500-800 times dilution or 50% thiophanate wettable powder at 500-800 times dilution.
Commonly used agents: carbendazim, thiophanate.