Influence of Culture Media and Environmental Factors (Water Potential and Temperature) on Mycelial Growth of Phytopythium vexans (de Bary), the Causal Agent of Dieback Disease in Apple Trees

This study aimed at evaluating the effects of culture media and environmental factors (temperature water potential (Ψw)) on growth pathogenic fungus Phytopythium vexans (de Bary) associated with root rot dieback disease in apple trees. Tomato agar, potato dextrose agar (PDA), soybean were most favourable for rapid mycelial growth, optimum recorded PDA medium. To determine conditions that promoted development this phytopathogen, temperature (5–30 °C), (Ψw) (−15.54; −0.67 MPa) (0.89–0.995 aw), their interaction evaluated vitro radial rates five isolates P. latency phase (time period prior to growth). The results showed temperature, potential, had significant (p < 0.001) phases all tested isolates. All able grow throughout range (5 30 maximum rate being observed highest temperatures, 25–30 °C. Growth was seen be faster MPa (0.995 aw) 25 °C No Ψw −5.44 (0.96 regardless temperature. It found length depended significantly both factors. longest days average) a 5 −2.69 (0.98 while shortest an average 0.2 days. findings from could help understand impact these occurrence diseases caused by more likely design reliable preventive control strategy based avoidance play favour phytopathogen.