Hibiscus can be prone to a variety of pests and conditions in the landscape, with some more controllable than others. Many times improper drainage and air circulation creates an environment for various pests and diseases to attack hibiscus plants. Hibiscus prefers well-draining soils and good air circulation for proper growth. Plants are sensitive to certain pesticides, so gardeners should read the label before applying and apply the product during a shady portion of the day.
Pink Hibiscus Mealybug
Pink hibiscus mealybug (Maconellicoccus hirsutus) is probably the worst pest condition affecting hibiscus plants. The bugs are very small, pink, covered in waxy secretions and when crushed the body fluids are pink too. They are a serious pest to hibiscus as well as other ornamentals grown in tropical and subtropical regions. The pest sucks out and lives on the plant's juices, with large populations being hard to control.
The mealybugs distort the hibiscus leaves by leaving them crinkled, twisted, bunched and unopened, including any new shoots. A white, fluffy mass resembling cotton candy covers the plant, with flower buds not opening and falling from the plant. Gardeners should trim the infected parts off the plant or remove the entire plant and discard it, as recommended by the University of Florida. Gardeners can use a contact or systemic pesticide on the plant to kill the pest.
Mushroom Root Rot
Insufficient draining in the planting site generally causes mushroom root rot in hibiscus. Hibiscuses grown in areas that have a tendency to collect water and retain moisture are more susceptible to the condition. The first sign of the mushroom root rot is the plant's foliage begins to wilt and within a short period, the hibiscus plant dies. Gardeners have no choice but to remove the entire plant, including the roots, and discard it as there is no saving the affected plant. The existing soil then requires replacement or sterilization before planting another plant species in the location. Gardeners should select a better draining site for the replacement hibiscus so it does not develop root rot.
Leaf spot is a common, less problematic situation occurring in hibiscus plants. Yellow or brown spots occur on the plants foliage. Caused by a variety of fungi or bacteria, the spotting is not life threatening to the hibiscus plant itself, but only to the affected leaves. The basic care for leaf spot is to remove the spotted leaves from the plant and surrounding area beneath the plant and destroy them.