One of the most common fungi found in flower beds in Arkansas consists of leaf and flower gall. The disease commonly appears among azaleas, camellias and rhododendrons growing in southern gardens. The fungus often attacks young leaves in wet areas but rarely causes problems in sunny, dry gardens. Choosing disease-resistant flowers and plants offers one way to keep the fungi to a minimum.
Plants with leaf and flower gall develop swollen green, fleshy areas. Sometimes the plants develop ugly galls of different sizes and shapes that appear on the leaves or flowers of the plants. The galls usually develop a white growth of fungus once mature, although the galls themselves appear pink or green.
The disease causes plants, especially azaleas and camellias, to look deformed. Diseased leaves appear up to 4 times as big as normal. The leaves also look thick or spongy. The galls get bigger before they eventually dry up and fall off the plant. Leaves growing in the shade near the bottom of the plant tend to develop more galls.
Leaf and gall fungi produce microscopic spores that come from the white growth that appears on the galls. The spores spend the winter on the buds of the plants. In the spring, the spores infect the new buds and flowers once the plants come out of the dormant period.
Foliage on young plants remains most susceptible to leaf and flower gall. The fungi first attacks the lower leaves, forming galls on the new foliage. High humidity and leaves staying wet, especially during long periods of rain, offer the perfect environment for leaf and gall fungi to live and grow. Poor air circulation, especially near the bottom of the plants, also causes the fungi to infect the leaves.
Handpicking and destroying the new galls helps keep the fungi from spreading. Pruning plants with damaged leaves and twigs also keeps the disease at bay. The key to pruning and handpicking requires removing the infected areas before the galls turn white. Otherwise, the tiny spores have already spread. Other control measures include increasing aeration around the plants to help wet leaves dry more quickly. Keeping the soil well-aerated also helps the plants become less susceptible to the disease.
The use of fungicides can help commercial growing operations control leaf and gall fungi. But in the garden, fungicides provide little relief for flower beds once the galls appear. According to the University of Arkansas, fungicides that might work in the garden should contain mancozeb, triadimefon or myclobutanil.