Phytophthora root rot (Phytophthora cinnamomi) may occur at poorly drained sites or in low areas of fields.
- Early above-ground symptoms include:
- Leaves turn yellow.
- Leaf margins burn.
- No new leaf growth
- As disease progresses:
- Terminal leaves become small
- Excessive defoliation occurs because of severely damaged roots.
- Stunted and wilt-prone leaves.
- Restricted root system that allows plants to be easily rocked back and forth, or pulled up.
- Dead or prematurely defoliating bushes.
- Defoliation and poor growth follow the contours of the low areas where excessive moisture is present.
Disease Cycle includes:
- Zoospores (swimming spores) produced by the fungus infect blueberry roots.
- Roots collapse and decay.
- Defoliation and poor growth follow the contours of the low areas where excessive soil moisture is present.
- Abundant soil moisture and temperatures between 68 F and 90 F (20 C to 32 C) promote disease development.
Control Measures include:
- Having adequate ditches.
- Planting on raised single-bedded rows.
- Taper-disking or sweep-blading.
- Using “sock pipe” and other types of pipe normally used for residential septic fields for draining small areas.
- Incorporating peat or bark mulch and, then, planting shallow and using additional mulch to form beds if planting on wet clay or clay loam soils.
- Benson, D.M. and R.K. Jones. Phytophthora Root Rot and its Control on Established Woody Ornamentals. 2000. Retrieved 19 October 2011.
- Cline, W.O. “Bill,” and Annemiek Schilder. Michigan Blueberry Facts: Phytophthora root rot. 2009. Retrieved 26 April 2010.
- Milholland, R.D. 1995. Phytophthora root rot. Pages 7-8 in: Compendium of Blueberry and Cranberry Diseases. F.L. Caruso and D.C. Ramsdell, eds. APS Press, St. Paul, MN. 87 pp.caetegory:blueberry diseases