Roses are a popular landscape and garden plant in Indiana. Black spot, caused by the fungus Diplocarpon rosae, is the major foliar disease of roses in Indiana. Infected leaves develop black spots, turn yellow and drop prematurely from the plant. Premature defoliation decreases plant energy reserves and results in reduced flowering of roses as well[Read More…]
Gail E. Ruhl
To effectively control Taphrina leaf curl fungicides must be applied before bud swell. If you remember seeing red, curled, distorted, leaves on Prunus spp. last year (Figs 1,2) and wondered what might have caused this symptom, the answer is most likely Taphrina leaf curl. Taphrina is a fungal disease that survives in bark and bud[Read More…]
Are you noticing bright yellow, white and brown blobs on wood chip mulch? These growths are known as slime molds. Slime molds are not parasitic and therefore do not cause disease. Slime molds get their nutrients from bacteria and small bits of organic matter which is why it is common to see them growing on[Read More…]
Slime flux (also known as wet wood) is a dark, foul-smelling and unsightly seepage of sap from tree trunks (fig. 1). The disease is not usually a serious problem but the appearance can be alarming. Slime flux is caused by common surface-inhabiting bacteria or yeast fungi that enter the trunk through wounds associated with improper[Read More…]
Have you ever noticed the fuzzy growth (Fig1) on the underside of an oak or sycamore leaf and wondered what was wrong with the tree? Fuzzy mats of hairy growth on the underside of tree leaves (Fig 2) are often mistaken for a plant disease or insect problem. In actuality, the whitish-tan fuzzy growth is[Read More…]
Oak leaf blister is caused by the fungus Taphrina caerulescens. Infections occur as buds swell and open during wet, spring conditions. Leaf blister symptoms usually appear within several weeks following infection as 1/4-1/2 inch circular, light green bulges on the top surface of leaves.(Fig 1) From the underside, the affected areas are sunken or depressed. These[Read More…]
Volutella stem and leaf blight, caused by the fungal pathogen Coccinonectria pachysandricola (=Volutella pachysandricola), can cause major damage to Pachysandra – destroying large areas in a bed. (Fig 1) Infected leaves first develop tan or brown blotches with dark brown margins, which expand, often with concentric lighter and darker target-like zones. (Figs 2a,b) Stem and[Read More…]
Bacterial leaf scorch (BLS) on oak is a systemic disease caused by the bacterium Xylella fastidiosa (Xf) (Fig 1). The bacteria live in the xylem vessels (water conducting elements) and restrict water flow. Xf is transmitted from tree to tree by xylem-feeding insects such as leafhoppers and treehoppers. Numerous woody hosts are susceptible to various[Read More…]
Tubakia leaf spot, a fungal disease, infects all species of oak. However, oaks in the red oak group such as black, red and pin oak, appear to be most susceptible. Symptoms on oak include small to large dark brown or reddish-brown spots or blotches. (Figs 1,2,3) Spotting that occurs on leaf veins may cause large[Read More…]
Boxwoods losing leaves should not be ignored!! Check them carefully for tell-tale symptoms of boxwood blight, a serious fungal disease that causes rapid defoliation and dieback (Fig. 1). The fungus that causes boxwood blight can infect all above ground portions of the shrub. The first symptoms of the disease are dark leaf spots (Fig. 2[Read More…]
Getting calls from panicked customers about black spots on maple leaves? You’re probably not alone, because now is the time when people start to notice maple tar spot. Every summer we get questions about black spots on maple leaves that look like tar. These spots are not actually “tar” on maple, but are rather a[Read More…]
One of the most common problems of broadleaf shade trees is a group of diseases collectively known as anthracnose. Anthracnose diseases are caused by fungi and become severe when cool, wet spring weather persists as leaves are first emerging. The most commonly affected trees are ash, white oak, maple, and sycamore. Dogwood, birch, elm, walnut,[Read More…]
The Purdue Plant and Pest Diagnostic Lab (PPDL) recently received samples of Mugo Pine and Spruce that exhibited reddish-brown bands on needles of lower branches (Figs 1 & 2). Microscopic examination of needles confirmed the presence of Dothistroma,(Fig 3) a fungus that causes red band needle blight. Needles infected with Dothistroma first exhibit dark green[Read More…]
Three different rust fungi cause gall-like protrusions on eastern red cedar (Juniperus virginiana) trees. The bright orange gelatinous galls with tendril-like protrusions (Fig 1) resembling ‘koosh balls’ are caused by Gymnosporangium juniperi-virginianae. This fungal disease is known as Cedar Apple Rust. The galls develop on the cedar tree (Fig 2) and ‘sprout’ fungal spore-bearing tendrils during[Read More…]
There may still be time to protect Prunus spp. from Taphrina leaf curl. Do you remember seeing red, curled, distorted, leaves on Prunus spp. last year and wondering what might have caused this symptom? Taphrina leaf curl, a fungal disease that survives in bark and bud scales, infects peaches and nectarines as well as ornamental[Read More…]
