Pineapple Diseases

Heart Rot

• Heart rot can occur on pineapple plants in the house as well as in the garden. Caused by a fungal infection, heart rot blackens the central leaves and makes them loose and easy to pull out of the plant. Pouring fungicide into the heart of the plant may rescue it from disease. If the plant survives, it will produce a new side shoot and concentrate its efforts on that instead of the old plant. You can cut this shoot off and pot it up or plant it in the yard. Discard the old plant.

Rots

• Phytophthora and Pythium fungi can attack and kill the pineapple's root system, destroying the entire plant. Look for reduced growth and vigor, reddened leaves and brown leaf margins. Rot can progress through the upper areas of the plant and ruin the fruit. Make sure the pineapple is disease-free before planting and institute a program of regular fungicide applications to control rot. Base rot is caused by the fungus Ceratocystis paradoxa, and butt rot is caused by Thielaviopsis paradoxa, which may also cause the pineapple fruit to rot during storage. The fungus thrives in moist conditions and generally develops when the plants are growing in poorly-drained soil. Improve drainage and do not over-water the plants. Keep gardening equipment clean and sanitized to avoid spreading infection to other plants. Remove and destroy plant debris and infected plants that are beyond saving.

Mealybug Wilt

• Mealybug wilt causes pineapple leaves to take on a reddish cast. The disease also causes leaf tip dieback and the leaves may curl downward and become limp. The disease is transmitted by the pink mealybug (Dysmicoccus brevipes) and the gray mealybug (D. neobrevipes). Ants attracted to the honeydew secreted by the mealybugs protect the insects in exchange for the honeydew. In addition to the symbiotic relationship between the ants and mealybugs, honeydew provides an excellent medium for another fungal infection, sooty mold, which causes black fruiting bodies to form on the plant. Kill the ants to allow natural predators the opportunity to attack and eliminate the mealybugs.

Yellow Spot Virus

• Transmitted by a tiny insect called a thrip, pineapple yellow spot virus is synonymous with tomato spotted wilt tospovirus. Thrip larvae feeding on the pineapple plant transmit the disease and can infect the plant in as little as 15 minutes. Leaves develop yellow spots and necrotic streaks. The fruit may also develop yellow areas with concentric rings. The virus is untreatable, so the only control method is to eliminate the thrips with insecticides and practice good sanitation methods in the garden. Remove and destroy all weeds, which may harbor adult thrips. Remove and destroy the infected plants.