Citrus fruits are the most popular type of fruit grown in Louisiana. At this time of year, satsumas and other citrus fruits are abundant and delicious.
However, various biotic and abiotic stresses affect citrus yields and can discourage home gardeners when they cannot enjoy their harvest.
One problem faced by citrus growers is internal dry rot of the fruit. Ripe fruit affected by this condition may appear healthy on the outside, but peeling the fruit reveals dry, discolored flesh. This internal dry rot is caused by a yeast called Nematospora coryli transmitted by the western leaf bug (Leptoglossus zonatus).
The leaf bug is widespread and a pest of many crops, including fruits, vegetables, cereals, nuts and ornamentals. It is a major pest of citrus and mainly attacks satsuma tangerines. It feeds by inserting its piercing-sucking mouthparts into the fruit. Feeding on ripe fruit causes premature color breakdown and fruit drop. Lesions usually occur as the fruit ripens in the fall. While feeding, the leaf bug transmits the yeast responsible for internal dry rot.
Adults can fly considerable distances and move from other crops to satsumas in the fall during fruit ripening. Leaf insects will congregate in large colonies on individual trees, while neighboring trees are completely free of insects.
Adult insects are dark brown in color and their hind legs are flattened and look like leaves. Nymphs, or immature insects, look completely different from adult insects. Its body color ranges from orange to reddish brown with black legs.
Leafhoppers are primarily managed using insecticides, but biological control is also available with other insects and entomopathogenic fungi. Homeowners can spray horticultural oils or Malathion 57EC to manage leafhoppers on yard trees. Just remember: Do not spray Malathion on plants in full bloom and be sure to wait at least seven days after spraying to harvest fruit.
Another problem citrus growers can encounter is bloated fruit. Swollen, misshapen fruit is primarily a problem on young, vigorously growing satsuma trees. As the tree ages, the appearance of swollen fruits decreases. Swollen fruit on older trees is the result of late-blooming fruit during periods of warm weather.
Puffy satsumas have thick, wrinkled skin and appear pear-shaped compared to the round, smooth, healthy fruits. When peeled, satsumas look dry and have no juice.
Little can be done to prevent bloated fruit. But good growing conditions, proper fertility and pest control are always helpful in keeping your citrus trees healthy.
