Friday, June 21, 2013

Phytophthora root and crown rot ALERT!

Recently, the U of I  Plant Clinic, has diagnosed many different plants with Phytophthora root or crown rot. Phytophthora is a genus of soil borne, fungal-like organisms that cause root, stem, and/or crown rot on many, susceptible plants including field crops, fruits, vegetables, trees, and shrubs. Different species of Phytophthora will prefer cool or warm weather, but all of them like it wet, which is one reason they are commonly referred to as water molds. This season has been especially, conducive to Phytophthora infection with an extended spring bringing excessive rainfall. Below are a few examples of different plant samples that have been received and diagnosed with Phytophthora crown and root rot at the Plant Clinic.  Management and links to more information on Phytophthora root/crown rot on trees and shrubs, fruits and vegetables, and soybeans are below.

Phytophthora root and crown rot on a Juniper from a nursery.

Phytophthora root and crown rot on soybean.

Phytophthora crown and root rot on red raspberry.
There is no simple "cure" for Phytophthora root and crown rot disease. Prevention and proper cultural practices are the best way to avoid or minimize losses. It's better to develop an integrated disease management to conquer this disease. Many methods are available, such as site selection, resistance species selection, fungicide application, etc.

1.  Exclusion - Buy healthy plants.  If possible only buy plants that come directly form the greenhouse and have not been grown in nursery fields before sale.
2.  Good Health - Place plants in proper location, plant properly, and keep in good vigor
3.  Drainage - Avoid overwatering, low lying areas, or plant in raised beds
4.  Resistance - Choose plants that are not as susceptible or tolerant to Phytophthora sp.
5. Fungicide/seed treatment - gives partial control and is only used in commercial growing situations

Phythophthora on Trees and Shrubs:

Phytophthora on Fruits and Vegetables:

Phytophthora on Soybeans:

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