What Causes Citrus Flyspeck – Treating Symptoms Of Flyspeck Fungus

Growing citrus trees can be a great joy, providing a beautiful landscaping element, shade, screening, and, of course, delicious, homegrown fruit. However, there is nothing worse than going to harvest your oranges or grapefruits and finding they have been damaged by flyspeck fungus.

Spotting Flyspeck on Citrus

Citrus flyspeck is a disease that may affect any type of citrus tree, but it is confined to the fruit. Look for small black dots, or specks the size of a small fly, on the rind of citrus fruits. The specks are typically seen near the oil glands, and they prevent that part of the fruit from turning color. The area of the rind with the specks generally stays green or sometimes yellow, depending on the type of fruit. There may also be a sooty covering on the rind, but this sometimes disappears, leaving just the flyspecks.

What Causes Citrus Flyspeck?

Citrus flyspeck is a disease caused by a fungus called Leptothyrium pomi. There may be other species of fungus that cause the infection as well. The sooty covering and the small black spots are fungus strands, not spores. How the fungus spreads is not fully understood, but it is likely that pieces of the sooty-like material break off and are blown from one citrus tree to another.

Treating Citrus Flyspeck

The good news about citrus flyspeck is that it doesn’t actually damage the internal quality of the fruit. You can still eat or juice the fruits, even with the specks present. The fruits don’t look very nice, though, and if you want to treat your tree, you can try an antifungal spray recommended by your local nursery or agricultural extension. You can also wash off the fungus after picking the fruit. How to prevent citrus flyspeck is also not well understood, but with most types of fungus, it’s important to avoid getting the leaves or fruit wet and provide plenty of space for airflow. Flyspeck may ruin the appearance of your citrus tree, but it doesn’t have to ruin the enjoyment of your lemons, limes, oranges, and other citrus fruit.

Mary Ellen Ellis

Mary Ellen Ellis has been gardening for over 20 years. With degrees in Chemistry and Biology, Mary Ellen's specialties are flowers, native plants, and herbs.