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ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #169005
Title: EFFECTS OF PRE-PLANT FALLOW AND CROP ROTATIONS ON SEVERITY OF PRUNUS REPLANT DISEASE

Author
item Browne, Greg
item SCHNEIDER, S - UC DAVIS PLANT PATH
item TROUT, T - UC DAVIS PLANT PATH

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2004
Publication Date: 7/1/2004
Citation: Browne, G.T., Schneider, S.M., Trout, T.J. 2004. Effects of pre-plant fallow and crop rotations on severity of prunus replant disease. Phytopathology.

Interpretive Summary: Prunus replant disease (PRD) causes stunting (mild cases) and tree death (severe cases) in young almond trees planted on sites with a recent history of Prunus cultivation. Pre-plant fumigation can prevent PRD, but little is known about controlling it with cultural or biological approaches. We evaluated short-term fallow and cover crop rotations for PRD control near Parlier, CA. Microplots (60 cm dia., 120 cm deep) were filled with soil from a PRD-affected orchard in Apr 2002. Treatments (2002) included: 1) almond on Nemaguard peach rootstock (A/NG) Jun-Nov; 2) A/NG Jun-Nov + methyl bromide:chloropicrin (MBP) (50:50, 448 kg/ha, Nov); 3) bare fallow Apr-Nov; 4) fallow Apr-Nov + MBP Nov; 5) field corn Jun-Nov; 6) Piper sudan grass Jun-Nov; 7) Penewawa wheat Nov-Mar; and 8) Piper Sudan Jun-Nov + Penewawa wheat Nov-Mar; each on five replicate plots. After each crop's growth period, the roots (sudan, A/NG) or roots and shoots (corn, wheat) were chopped and incorporated into the soil. Treatment efficacy was assessed according to growth of Nemaguard peach seedlings, planted four per plot Apr 2003, weighed Nov 2003. Treatment effects were significant (P<0.0001); the means were separated with 95% CIs. Compared to the non-fumigated, non-fallowed A/NG control (Trt. 1), which had stunted plants, fallow+MBP increased peach shoot mass by 286%. Also, MBP alone, or sudan or wheat increased shoot mass (157, 132, and 135%, respectively), but fallow alone and the other rotations did not. Sudan or wheat rotation may help manage PRD, and confirmation is underway.

Technical Abstract: Prunus replant disease (PRD) causes stunting (mild cases) and tree death (severe cases) in young almond trees planted on sites with a recent history of Prunus cultivation. Pre-plant fumigation can prevent PRD, but little is known about controlling it with cultural or biological approaches. We evaluated short-term fallow and cover crop rotations for PRD control near Parlier, CA. Microplots (60 cm dia., 120 cm deep) were filled with soil from a PRD-affected orchard in Apr 2002. Treatments (2002) included: 1) almond on Nemaguard peach rootstock (A/NG) Jun-Nov; 2) A/NG Jun-Nov + methyl bromide:chloropicrin (MBP) (50:50, 448 kg/ha, Nov); 3) bare fallow Apr-Nov; 4) fallow Apr-Nov + MBP Nov; 5) field corn Jun-Nov; 6) Piper sudan grass Jun-Nov; 7) Penewawa wheat Nov-Mar; and 8) Piper Sudan Jun-Nov + Penewawa wheat Nov-Mar; each on five replicate plots. After each crop's growth period, the roots (sudan, A/NG) or roots and shoots (corn, wheat) were chopped and incorporated into the soil. Treatment efficacy was assessed according to growth of Nemaguard peach seedlings, planted four per plot Apr 2003, weighed Nov 2003. Treatment effects were significant (P<0.0001); the means were separated with 95% CIs. Compared to the non-fumigated, non-fallowed A/NG control (Trt. 1), which had stunted plants, fallow+MBP increased peach shoot mass by 286%. Also, MBP alone, or sudan or wheat increased shoot mass (157, 132, and 135%, respectively), but fallow alone and the other rotations did not. Sudan or wheat rotation may help manage PRD, and confirmation is underway.