The influence of climatic conditions on the occurrence of powdery mildew attack in oak forests in Mures County, Romania

Powdery mildew attack represents an important issue, which must be taken in consideration in forest management. The Transylvanian climate conditions are characterized by major variations induced by the climatic changes of the past decades. Both soil and climate conditions were analyzed, and in the end several statistic analysis were made. It can be observed, from the collected data, that the studied area is characterized by high humidity, a factor that correlated with the drying phenomena presents high risk to the forest, being capable of inducing powdery mildew, a disease that is produced by a fungus, Microsphaera abbreviata. The appearance of the disease is favored by climatic factors, the infections happen when the daily temperature reaches values over 15oC and the atmospheric humidity at the level of the leaf is about 80%. The mycelium appears on the upper part of the leaves, and the attack is seen as white spots which are progressively enlarged, and in the end they contribute at the drying of the tree. Key Words: Forestry, fungus, humidity, drying, Microsphaera abbreviata. Rezumat. Atacul făinării reprezintă o problema importantă, care trebuie luată în considerare în procesul de management al pădurii. În zona analizată au fost condiţii de umiditate crescută, care împreună cu fenomenul de uscare a crescut riscul de atac a făinării împotriva pădurii. Au fost analizate resursele de sol precum si condițiile climatice și s-a realizat analiza statistică a datelor obținute. Apariţia făinării este favorizată de temperaturi medii peste 15oC şi de o umiditate atmosferică de peste 80%. Atacul ciupercii apare pe suprafaţă superioară a frunzei sub aspect de pete albicioase şi continuă până în momentul uscării complete a frunzei.