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Plant NameTypeDescription 
AnthracnoseAshDiseaseAnthracnose is a fungal disease of leaves and twigs of many ash species, including black, green, red, velvet, and white ash. Symptoms of anthracnose arise in spring on succulent, expanding shoots and leaves as water-soaked spots that may enlarge and coalesce rapidly. Young leaves may be severely deformed (curled, puckered, or twisted) by infections occurring during development. Later symptoms include the presence of small to large irregular brown lesions on the leaves, usually along the midrib or main veins. Half or more of a leaf may be killed. Twigs may develop cankers and die back. The fungus may be visible as small brown specks on the lower surface of infected leaves or as pustules on infected twigs. Infections of mature, more resistant leaves are often limited to small brown spots. The fungus may infect and girdle twigs, also and cause premature leaf drop. The disease is favored by prolonged moisture at the time leaves are developing. Symptoms appear on lower part of tree; in severe cases, they can progress to the top of the tree. Defoliation in several successive years may lead to dieback.
Nectria cankerAshDiseaseNectria canker is a fungal disease often found on twigs and branches that have been weakened by drought, frost damage, insect damage, or other diseases. Cankers are initially distinguished by discolored bark with coral or reddish fungal fruiting bodies. The cankers are sunken and often associated with wounds. Older cankers develop concentric, target-like rings of wood. Affected branches may have stunted or wilted leaves, or fail to produce leaves in the spring. Branches may be girdled.
AphidsAshInsectAphids are small, soft-bodied insects that typically feed near the tip of growing shoots. Their feeding may deform leaves (curling, distortion) and stunt terminal growth. Aphids range in size up to 1/8" long and often produce honeydew, a sweet sticky material. The honeydew may develop a growth of black sooty mold, which is an aesthetic problem but seldom harms the plant. It may also attract honeydew-feeding ants.
Ash borerAshInsectThe ash borer, also known as the lilac borer, is a member of the clearwing moth family. The adults of many clearwing moths mimic yellowjackets or paper wasps. The larvae of this moth cause damage to ash, lilac, and privet. The larvae tunnel in the bark of stems (trunk) and branches causing a gradual weakening of the plant. Other than emergence holes, one can determine the pests' presence by the pupal skeletons attached to the bark at the emergence sites. There is usually only one generation per year. However, a two-year cycle can occur in the northern part of its range. Adult numbers usually peak in May or June and females lay their eggs singly in bark crevices where they soon hatch and burrow their way into the phloem tissue and continue feeding. Emerging full-grown larvae produce a round hole about 1/16 inch in diameter. Urban, open grown trees are highly susceptible to infestation.