Symptoms
Spanish or Red Oaks infected with the Oak Wilt fungus will often form fungal mats on the trunk area and often die within one to four weeks, while Live Oaks may die within a period ranging from one month to two years. Infected Live Oak trees show browning of the leaves on individual limbs. Also, leaves on infected limbs will show specific patterns of chlorosis or yellowing. Defoliation occurs quickly after symptoms are observed.
Figure 4-11. Veinal leaf necrosis of Live Oak leaves infected with the Oak Wilt fungus.
Figure 4-12. Veinal leaf necrosis of Red Oak leaves infested with the Oak Wilt fungus.