Gardening Blog

Gardening Blog: Plum Pockets

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Spring is almost here and now is the time to take preventative measures against a number of possible fruit tree diseases.

Spring is just around the corner and it is time to start getting the garden back in order. If you have cherry, plum, wild plum, apricot or wild cherry trees then this is the time for applying preventive fungicides to protect against the damaging plum pocket disease. Preventative fungicides help to destroy overwintering fungal spores on trees that start to grow and infect trees in spring.

What Is It?

Plum pocket is a fungal disease that is caused by a number of Taphrina fungi. The fungi infect fruit and lead to the development of large, hollow, bladder like pockets around the fruit. Infected fruit enlarges to up to 10 times its original size. The commercial plum varieties from Asia and Europe are not susceptible to plum pockets.

Symptoms

The disease starts with the appearance of small, white spots on fruit skin. Spots gradually enlarge to cover entire fruit. Affected fruit fails to develop any seeds. The pockets on fruit differ in color from a greenish-yellow to a bright red. Cherries get very red and grow in a pointed shape. Plums have a red to gray tint. Shoots on affected trees are deformed and thickened. Foliage is curled and branches grow in clusters. The pockets around the fruit start to develop mold during moist or humid weather. Bark and foliage appears velvety, sooty and dark. The fungal spores wedge in tree crevices and bud scales and overwinter. Infection in the following spring is the result of these overwintering spores. Spores germinate rapidly during the moist spring weather.

What to Do?

Using preventive fungicides is among the best ways to protect trees from infection. This includes dormant season spray of lime sulfur or Bordeaux mixture. Mix 10 tablespoons of lime sulfur in a gallon of water and spray on trees. This is most effective just prior to bud swell on trees. Do not use when leaves are still present on trees as this can burn the foliage. Make sure you reach all the crevices and folds in the bark. Follow directions on Bordeaux for correct method of application.

Similar Damage

Damage in chokecherries resulting from a small sized fly called by chokecherry midge results in similar symptoms. The pest lays eggs on young fruit and the larvae feed into the fruit, creating tunnels and hollowing out the centers. Affected fruit turns green and swollen, often splitting to reveal reddish-yellow maggots. There are few control options that control the pest. Fungicides for plum pockets do not control chokeberry midge.

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