DISEASE

NAME
Twig Blight
Phomopsis juniperovora

Description
PhomopsisTwig Blight of Juniperis a fungus problem commonly known as cedar, juniper, or needle blight and is normally a leaf or shoot infection commonly found in young plants and on the new growth of older plants.

Symptoms
The tips of young needles form yellow spots and as the infection progresses from the needle to the stem the infected area turns red brown to ash grey associated with dieback. If allowed to continue the entire branch dies as the fungus mycelium progresses into the main stem. It grows rapidly along the inner bark, killing the cambium and turning the wood brown.

Liquidambarspecies

Lesions occur on the stems; these frequently develop into cankers at the point of healthy and diseased tissue. The canker can girdle the branch of young plants, but older plants are more resistant. Young or small plants may be completely covered in the fungus turning the plant brown.
Only immature needles are affected and when the needled turn deep dark green they are not susceptible to the disease. As the infection matures small black spots or fruiting bodies may be seen using a magnifying glass on the dries grey areas.

Source and Dispersal
The fungal spores (conidia) are dispersed by wind, insects and from infected plants or parts of plants that are trimmed from the tree. It is also dispersed by splashing water or contaminated stock. Overhead irrigation especially in nurseries is conducive to infection. The fungus will not die if the host becomes dry but will continue growing when moisture returns.

Favoured Conditions
The fungus prefers cool humid climates or 15 ° to 27 ° C (60 ° to 82° F) and is not commonly seen in warm coastal regions and may continue living in dead wood, leaf litter or harvested fruit for up to two years.

Affected Plants
Many plants are affected by this fungus such as (Thuja), species of true cedar (Cupressus), and false cedar (Chamaecyparis), European larch (Larixdecidua), jack pine (Pinusbanksiana), English yew (Taxusbaccata), Japanese plum yew (Cephalotaxus drupacea), Douglas fir (Pseudotsugataxifolia), species of fir (Abies), and Cryptomeria japonica

Note
Listed below are otherTwig Blights generally specific to there host.

Abiesspecies are infected by Needle and Twig Blight(Rehmiellopsis balsameae), turning the current season`s needle growth reddish before dieing.

Cedrusspecies are infected by theTip Blight(Diplodia pinea) that forms cankers in branchlets causing die back.

Cercidiphyllum japonicumis susceptible to the twig blight (Phomopsis species), causing disfigurement of the branches.

Cordyline species are infected by the Tip Blight(Physalospora dracaenae) that turns the leaves light brown and dry from the tips down, affecting the lower ones first.

Cornusspecies are susceptible to three types of Twig Blight (Myxosporium everhartii), (Cryptostictis species) and (Sphaeropsisspecies). These fungi form cankers or blighting on the twigs.

Euonymus species are suseptable to Phomopsis Dieback(Phomopsis species). This causes the twigs and small branches to die back and mild cases are not normally detrimental to the plants growth.

Laburnum anagyroidesis infected by the Twig Blight(Fusarium lateritium) causing brown lesions to appear in the twigs and progressing to blight the leaves appearing as wet areas.

Ligustrumspecies are susceptible to the Nodular Gall(Phomopsis species). This fungus causes small 25mm wide galls to appear on the plant. The fungus normally gains access through moist damaged tissue.

Liquidambarspecies are infected by the Twig Blight (Phomopsis juniperovora) causing cankers along the stems.

Magnoliaspecies are susceptible to the Dieback(Phomopsis species). In these trees cankers form longitudinal cracks turning the bark dark brown and the heart wood blue-grey. Currently there is no known control and heavily affected plants should be removed.

Pinusspeciesare infected byCenangium Twig-Blight(Cenangium abietis) attacking the current season growth.

Salixspecies are infected by the twig blight (Physalospora miyabeana) that forms brown spots on the leaf upper surface and whitish lesions appear on the twigs.

Sequoiaspecies are infected by Needle Blight(Chloroscypha chloramela) which attacks the young growth.

Taxodium distichumis infected by the Twig Blight (Pestalotia funereal) that forms small spots on the leaves, cones and bark, normally during wet periods.

Non-chemical Control
Avoid watering plants from above or wetting the foliage especially in the late afternoon. When planting allow space between each plant for good air circulation.
Remove affected foliage or wood by pruning and dispose off site. In a nursery avoid having seedlings placed alongside older stock or using Junipers as a windbreak around the nursery. When planting susceptible plants avoid poorly drained soils.

Chemical Control
Regular spraying where possible during the periods that are favourable for fungus development. Fungicides include;
Systemic types, Biteranol, carbendazim, triforine
Protectants; chlorothalonil, copper oxychloride, mancozeb, thiram, zineb
Note
Always read the label for registration details and direction of use prior to application of any chemicals.