EPWS 310 - PLANT PATHOLOGY

Lecture 8: The Oomycetes

Contents of Lecture

3. Phytophthora Foot and Crown Rots

4. Phytophthora Leaf and Stem/Fruit blights

Order Peronosporales:

Pages 414 - 2427

Continue Phytophthora Root Rots

Chile root rot.

These fungi are able to infect most parts of the root system (cf. Pythium) and can grow along the root and up to the crown and stem. Control depends on resistance, good water management, rotation and careful chemical control (resistance).

3) PHYTOPHTHORA FOOT AND CROWN ROTS

Many Phytophthora species cause diseases of the lower stem of many woody hosts. such as nut trees, Citrus, avacado and forest trees. This causes decline dieback and death, P. cinnamomi, P. citrophthora (on citrus).

Injection of Phosphorous Acid (Fosetyl Al) and Metalaxyl have been very successful.

4) PHYTOPHTHORA LEAF AND STEM/FRUIT BLIGHTS

Many Phytophthora species have deciduous sporangia are moved by wind, P. infestans.

Rain splash and wind spreads sporangia and these diseases can be VERY serious.

P. infestans. Disease Cycle Figure 11-29

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