ISSN:
1573-5036
Keywords:
Avocado
;
Ca
;
Mn
;
Oxisol
;
P
;
pH
;
Phytophthora root rot
;
Soil water
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary This experiment employed a factorial design combining 4 soil pH levels, 3 soil moisture levels, with and without the addition ofPhytophthora cinnamomi to the soil to evaluate the conditions that lead to Phytophthora root rot of avocado. An inverse relation between soil pH and leaf production (and root-weight) was observed in nondiseased plants. In soil infested withP. cinnamomi, plant growth and root weights were much depressed by low soil pH, and especially by low soil pH coupled with high soil moisture contents. These interactions were statistically highly significant. Root weights in pots withP. cinnamomi were closely related to the incidence of disease. A disease index was used to visually assess the conditions of roots. Isolation of the pathogen from diseased plant roots confirmed the accuracy of the disease index. A process of elimination suggsts that favorable soil Ca level and not high pHper se was responsible for disease suppression and that the devastating effects of low soil pH was produced by high Mn (and possibly Al) and associated low levels of Ca and P in soil solutions, which led to breakdown of biological control mechanisms.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02197148
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