Diseases of Crotons
Crotons, a tropical garden plant, are native to Indonesia. Crotons are colorful shrubs that can be grown in U.S. Department of Agriculture hardiness zones 10a through 11, or indoors anywhere with proper care. Green, yellow, orange and red leaves make the croton a colorful attraction to any garden or décor. Generally, crotons are healthy plants, but can succumb to different diseases. If you notice a problem with the croton, diagnose the problem and treat accordingly to protect other plants around the croton.
Anthracnose (Colletotrichum sp), is a disease that leaves the croton leaves with tan dead spots according to the University of Florida. The fungal disease can spread quickly. Leaves affected with anthracnose must be removed immediately to prevent spreading. Plants that have the fungi can infect other plants if any infected leaves touch other healthy plant leaves. In cases of severe infestation, fungicide with a copper-based can be used, but some plants will need to be cut and destroyed.
Stem Gall and Canker
Stem gall and canker (Kutilakesa pironii) is a fungal wound pathogen that is somewhat similar to crown gall according to the University of Florida that can affect crotons. Although this fungal infection should be diagnosed by a pathologist to determine if it is crown gall or stem gall and canker and the best treatment to use if any, plants that have this fungal infection are commonly destroyed at once to prevent other plants from becoming infected. The disease produces callus tissue along the stem according to the Florida Department of Agriculture & Consumer Services Division of Plant Industry.
Crotons infected with crown gall (Agrobaterium tumefaciens), which creates swollen veins on the leaves and thick stems on the plant must be cut down and destroy according to the University of Florida. A bacterium typically develops where clippings have been taken. Once the plant has the bacteria, there is no cure. In order to prevent the disease from spreading to other crotons, the plant must be removed from the surroundings.
Xanthomonas Leaf Spot
Xanthomonas leaf spot is a tiny dot on a water soaked leaf, which rapidly spreads in size to 1/4 inch or larger according to the University of Florida. The bacterial is found between the leaf veins and appears blackish or brownish. Some spots may have a yellowish border. Bactericides with a copper based compound can be used for prevention, but plants with xanthomonas must be destroyed.
Growing Tips for Crotons
Crotons like a lot of sunlight, so grow them in a sunny spot. Being in a sunny area, allows a croton to grow all of those beautiful and colorful leaves. If the croton doesn't get enough light, the croton plant grows tall and lanky, with few leaves that don't have deep, rich hues.
Water your croton plants as soon as the soil starts to dry. If they stay too wet or too dry for a long period, their leaves will start to drop. A croton plant is not as thirsty as most other common houseplants.
Croton plants like plenty of humidity, if you grow them indoors, placing them in the kitchen or a bathroom where there is more humidity will be great. You can also place them near a small humidifier.
Fertilize croton plants during the spring and summer months to keep it healthy and growing. Crotons only need to be fertilized once or twice during the season, but you can get them to grow faster by fertilizing more frequently. Follow the directions on the fertilizer package whenever feeding your plants. Just be careful not to over fertilize.
They will grow well outside just as long as there is no frost, so in the United States, they will only do well in warm climates like south Florida, parts of Arizona, and southern California.