What are the symptoms and control methods of pear rust?

During the cultivation of pear trees, pest and disease attacks occur for various reasons, among which pear rust is a relatively common one, also known as red star disease. Once it occurs, it has a relatively large impact on the quantity and quality of the fruit. So what are the symptoms of pear rust? How to treat it?

I. What are the symptoms of pear rust?

Leaf infection: In the early stage, small orange-yellow, glossy spots appear on the upper surface of the leaves, which later gradually expand into nearly round lesions with an orange-yellow center and pale yellow edges, with a layer of yellow-green halo on the outermost part and densely covered with small yellow granules on the surface. When the weather is humid, pale yellow mucus oozes from them, and after drying, the small granules turn black. The lesion tissue gradually becomes thick and fleshy, the underside of the leaf bulges, the upper surface is slightly sunken, and grayish-yellow hairy growths emerge from the bulging parts.

Fruit infection: In the early stage, the lesions are roughly similar to those on the leaves, and in the later stage yellow hairy growths are produced. After the aecia mature, the tips rupture and release yellow-brown powder. The lesions then gradually turn black, and diseased leaves fall off easily.

Alternate host: When the host Chinese juniper is affected, pale yellow spots first appear on the needles, leaf axils or twigs, and then become slightly raised. In March of the second year after infection, they gradually break through the epidermis and expose red-brown or coffee-colored conical horn-like structures, which are telial horns. At the sites where telial horns occur on the twigs, the swelling is relatively obvious. After spring rain, the telial horns absorb water and swell, becoming orange-yellow tongue-shaped gelatinous masses, and when dry they shrink into dirty gelatinous matter with a wrinkled surface.

II. How to treat pear rust?

Pear rust causes spots of varying shapes to appear on pear tree leaves, and if left untreated for a long time, the lesions will spread, causing the entire pear tree to have spots and affecting flowering and fruiting as well as fruit yield. If pear rust occurs, it is necessary to promptly spray the fruit trees with some triadimefon emulsion and emulsifiable concentrate agents, which can effectively slow down the symptoms. It should not be used too much at one time; spraying once about every week is enough, and it only takes about four weeks to recover to normal. The amount sprayed should not be too much, as too much will also affect the growth of the pear tree. If the disease occurs during the flowering and fruiting period, the amount used should be halved.

If pear rust is found on a pear tree, it is first necessary to deal with it promptly. In sunny weather, prune it, cutting off all diseased branches and leaves, and let it be exposed to light, which is very effective for its recovery and can help the pear tree recover quickly. In addition to this, some appropriate amount of nitrogen and phosphorus fertilizer can be applied to increase the resistance of the pear tree. Well-rotted organic fertilizer can also be used to replace compound fertilizer, which has a very good recovery effect on pear trees after disease, and watering should be reduced during the recovery period.