Phytophthora root rot is a devastating plant disease caused by the soil-borne pathogen Phytophthora spp. that affects a wide range of plant species, including citrus trees such as oranges. The disease primarily affects the roots and can lead to severe damage or even death of the plant. Here are some symptoms of Phytophthora root rot that you should look out for in oranges:
- Root decay: Phytophthora root rot starts with the infection and decay of the roots. Affected roots appear brown, waterlogged, and may be soft and mushy. They may also have a foul odor.
- Wilting and yellowing leaves: As the disease progresses, the infected tree may exhibit wilting and yellowing of leaves. This symptom is often more pronounced during periods of hot weather or water stress.
- Stunted growth: Infected citrus trees may show reduced growth or overall stunted appearance. The tree may fail to develop new leaves, and existing leaves may be smaller than normal.
- Leaf drop: In severe cases, the infected tree may shed its leaves prematurely. This can result in significant defoliation, leaving the tree weak and susceptible to further damage.
- Dieback of branches: Phytophthora root rot can cause the dieback of branches, starting from the tips and progressing towards the main trunk. Infected branches may become discolored, turn brown, and eventually die.
- Dark brown cankers on the trunk: In advanced stages of the disease, dark brown cankers may develop on the trunk near the soil line. These cankers can girdle the tree, disrupting the flow of water and nutrients.
- Poor fruit quality: Infected citrus trees may produce fruits of inferior quality. The fruits may be smaller, misshapen, and may have a thick rind. The internal flesh may be discolored or show signs of rot.
If you notice these symptoms in your orange trees, it is important to take action promptly. Contact a local agricultural extension service or a professional horticulturist to diagnose the problem accurately and to discuss appropriate management strategies for Phytophthora root rot.
