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Prevent and control pear rust early, so the fruit does not grow warts

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The disease that causes warts on pear fruit is called rust, also known as pear rust, pear red rust, or pear-apple-juniper rust. Before the pear trees shed their leaves, in September, the disease successively transfers as mycelium to alternate hosts on juniper (including Chinese juniper and dragon juniper) type trees. As long as juniper type trees are planted, pear orchards have the possibility of rust occurring every year. After leaves are infected, orange-yellow oil-droplet-like small spots appear on the surface, gradually developing into nearly round lesions 4-8 mm in diameter, with orange-yellow small granular spots appearing in the center, which later gradually turn black; the area around the lesion is reddish-brown, the upper leaf surface is sunken, and the back

The disease that causes warts on pear fruit is called rust, also known as pear rust, pear red rust, or pear-apple-juniper rust. Before the pear trees shed their leaves, in September, the disease successively transfers as mycelium to alternate hosts on juniper (including Chinese juniper and dragon juniper) type trees. As long as juniper type trees are planted, pear orchards have the possibility of rust occurring every year. After leaves are infected, orange-yellow oil-droplet-like small spots appear on the surface, gradually developing into nearly round lesions 4-8 mm in diameter, with orange-yellow small granular spots appearing in the center, which later gradually turn black; the area around the lesion is reddish-brown, the upper leaf surface is sunken, the back is swollen and raised, and grayish-brown thin tube-like structures grow out vertically (looking coarse like brown hairs growing out), generally about 10 or more. When there are many lesions on diseased leaves, they often fall off early.

The symptoms of infected young fruit are the same as those of diseased leaves. Severely infected fruit drops early, while less severely infected fruit grows into deformed fruit, with one or several localized areas sunken due to the lesions, and this part of the flesh is like a hard wart and cannot be eaten. If spring rain comes early, the disease also occurs early; if there is a lot of spring rain, the disease is also severe. Conversely, if spring is dry with little rain, the disease occurs little or not at all in pear orchards.

The key to preventing and controlling pear rust is prevention. First, cut down all juniper type trees around your own pear orchard. If by any chance the junipers cannot be cut down, spray the junipers 1-2 times with 1-2 degree lime sulfur mixture before the pear trees bloom and leaf out, which can also effectively control the spread of the pathogen

Second, spray fungicides from after pear trees drop their flowers to the young fruit stage, which can effectively prevent the pathogen from invading and causing damage. The most commonly used pesticide and the one with good quality and low price is Bordeaux mixture, at a concentration of 1:2:200 (that is, 1 part copper sulfate, 2 parts quicklime, 200 parts water), prepared and used immediately, sprayed on sunny days after the dew has dried. You can also directly buy from the agricultural supply market 40% asomate (Asomate) wettable powder, mixed into a 500-fold solution; or 50% thiophanate-methyl (thiophanate-methyl) wettable powder, mixed into an 800-fold solution; or 65% zineb (Zineb, zincate) wettable powder, mixed into a 600-fold solution, for spraying. No matter which pesticide is used, once every 15 days, 2 consecutive times is enough to effectively prevent and control pathogen infection, and 3 times gives an even better effect.

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