Root and Stem Rot (fungus – Rhizoctonia solani): The fungus may attack roots, stems and lower leaves. symptoms on lower leaves first appear on those leaves in contact with the soil. Affected leaves are characterized by well-defined water-soaked areas which enlarge rapidly during cool, moist conditions. At first, leaves are dark green, they then wilt and turn dark-brown. Stems and roots may also be attacked. Infected areas are at first water-soaked in appearance and later become sunken and reddish-brown. Best control is obtained by planting only in sterilized beds. Beds should be well-drained. Soil fungicides applied as a drench around infected plants may be effective.
Root Rot (fungus – Phymatotrichum omnivorum): Affected plants wilt and die suddenly. Leaves of infected plants turn brown and remain on the plant. (See section on Cotton Root Rot)
Anthracnose (fungus – Colletotrichum omnivorum): A common disease of English ivy. Infected leaves have large tan-to-dark brown spots with a darker border. The center of infected areas may have small black spots formed by pycnidia (fruiting bodies of the fungus). Spots range in size from one-eighth inch to one-half inch in diameter. As the spots age, the centers may dry up and fall out giving a shredded or shot hole appearance. The fungus may also infect stems causing dark, sunken lesions. In some instances, the stem may be completely girdled causing death of the distal portion. Infected leaves should be picked off and destroyed. Avoid overhead watering. Foliar fungicide application at regular intervals are effective.
Bacterial Leaf Spot (bacteria – Xanthomonas spp.): Circular spots which are, at first, light green water-soaked areas. As the spots enlarge, they become brown-to-dark brown with red margins. Eventually, the center of the spots dry and crack. Young twigs and petioles are also attacked. Infection on stems and petioles causes a blackening and shriveling of the tissue. Cankers form and may girdle the stem. Tips of growing portions of the plant turn black and this blackening may extend downward into the older wood. Infected plants may fail to grow normally and have pale yellow-green foliage. Remove and destroy all infected plant tissue. Avoid overhead watering, overwatering and high temperatures, if possible.
Leaf Spots (fungi – Ramularia hedericola, Macrophoma spp., Glomerella cingulata, Phyllosticta concentrica): Brown lesions will occur on the leaves and may also infect the stem, causing girdling, collapse and death of apical portion. Infected leaves can be picked off and burned. Remaining foliage should be sprayed with a fungicide.
Sooty Mold (fungus, Capnodium sp., and others): The sooty mold fungus may develop on English ivy growing beneath certain trees. This mold lives on secretions of aphids and scale insects which fall from the tree above. This mold seldom causes damage. Control insects to prevent this problem.