Diseases
Cedar Quince Rust
Growers across the state are experiencing cedar quince rust on hawthorns. Cockspur hawthorn, Crataegus crusgalli var. inermis, is particularly susceptible. Cedar quince rust is devastating because the disease occurs as a canker rather than a leaf spot. Affected branches will die from the canker to the branch tip. The extended periods (48 hours) of wet weather this spring were ideal for infection. Unlike apple scab, there are no secondary cycles of hawthorn, so spraying now will not reduce the severity of this year's infection. Use weather data next spring to predict infection opportunities and precisely time fungicide applications.

Source: Compendium of Apples and Pears. APS Press.

Southern Blight
Southern Blight, Sclerotium rolfsii, is a fungal-caused disease that has caused significant losses in apple orchards, vegetable crops, and crabapples in Kentucky. For woody nursery crops, young plants without hardened bark at the collar-root interface or plants with wounded, mature bark are most susceptible. Hydrangea, crabapples, Prague viburnum, liriope and azaleas are susceptible. Symptoms are rapid wilting and plant death. The lower stem, soil, and root system have white mycelium webbing and round mustard seed-like sclerotia, which may remain viable in soil or potting substrate for years. Fungicide drenches, crop rotation, and raised production areas can reduce Southern Blight. Eliminating weed hosts and deep plowing to hasten decay of organic matter from weeds or cover crops well in advance of production production can help limit Southern blight. Southern blight is easily moved on implements, workers, and tools from field to field. Proper sanitation is essential to avoid contaminating fields, plants, and substrate with the sclerotia.

Source: Diseases of Woody Ornamentals and Trees in Nurseries. APS Press. 2001.

Cultural

Root System Woes
Pears have recently begun showing red leaf color and dying. The same plantings of pears also have purple interveinal scorch - like spots which have never yielded any disease-causing microbes. Inspection of root systems revealed stunted, girdling root systems.
Red leaves can mean a number of things; the following are two possibilities. Red leaves may mean that photosynthates have built up in the leaves because there is an inadequate or inaccessible root system (as in cankers or girdling roots) to store the sugars. Red leaves can also mean nutrient deficiencies. With small root systems nutrient deficiencies can occur in the immediate area around the roots but not exist between root systems within a row or in row middles. These phenomena have been documented in other crops. Trees growing in soils with a fragipan or otherwise shallow would be particularly prone to the development of inadequate root systems as would trees grown from liners with undesirable structure.

Root System Marketing
Girdling roots and planting depth are receiving attention in the horticulture industry. Select Trees in Athens, GA is making a comparison of competitors' roots and their enhanced root systems a selling point. "Root skeleton sacrifices" are found hanging from posts throughout the nursery next to inferior root systems from other nurseries. This effort is a demonstration to customers of their high quality, well-branched root systems which are otherwise hidden underground.

Pot-bound root system, unknown vendor.