Buckeye Yard and Garden onLine

Last week, BYGLers Erik Draper, Joe Boggs and Jim Chatfield went down to Lexington and UK's Plant Pathology Department and the relatively new main campus arboretum, for a short one-day Plant Pathatical with John. What glories?! Oozing masses of jelly-like teliospores from CEDAR APPLE RUST, CEDAR HAWTHORN RUST and CEDAR QUINCE RUST fungi on the stems of junipers, readied for their dissemination to their alternate rosaceous hosts including apple, crabapple, hawthorn and quince. As John pointed out, the maturation of these rust fungi on junipers is ultimately the result of the arrival of spores from their alternate rosaceous hosts in summer and fall about a year and a half ago. It was wet in that late season of 2006 and that is why it is a banner year for those oozing cedar rust spores now on their juniper hosts. Spores are spreading now to hawthorns and crabapples, but only for several weeks time, both in Kentucky and Ohio.

John also noted that SPHAEROPSIS (DIPLODIA) TIP BLIGHT had truly taken its toll on Austrian pine on UK's Lexington campus over the years. Since he  
arrived there and surveyed Pinus nigra in his first years, a full 84% of these pines have been removed by the UK's grounds maintenance professionals.  Not all of those removed were technically dead, but enough damage, especially to lower branches with infections spreading ever upward, had occurred that tree removal was warranted due to these plants being "horticulturally dead" - no longer serving their intended landscape function.  Over the year's John and his graduate students have done a good deal of important work on understanding the disease cycle for Sphaeropsis tip blight of pine, including showing the extent to which latent infections may occur, in many cases, months and years before symptoms and disease expression occurs.

At John's desk, using the Mary Blight computer model, John was able to follow the occurrence of conditions for BACTERIAL FIRE BLIGHT OF APPLES, PEARS and CRABAPPLES as they developed across Kentucky.  As with all diseases, infection and disease development depend upon specific factors.  A key for serious fireblight outbreaks is whether or not significant blossom infection occurs; infections of other plant parts can also result in infection later, but major outbreaks are typically due to several days of temperatures in the 60s when petals, pistils and then nectaries of the flowers are out and are infected by the buildup of inoculum during this relatively warm spring weather when moisture is also present.  Temperature averaging 60F for a day after infection is then also a major factor.  All the details are imbedded in John's Mary Blight program that he shares with the growers in the different areas of Kentucky.  We shall miss ye, John!