Chemistry Reference
In-Depth Information
Table 8
Common soil-borne pathogens on major field crops in the tropics.
Pest/Pathogen
Diseases
Common host crops
Reference
Fungi
Fusarium spp.
d
n
1
r
2
n
g
|
4
Wilt, crow rot,
blackleg
Vegetables, banana, bean,
coffee, cotton, melon, potato,
tomato, cowpea, Crotalaria
spp., Sesbania spp.
6, 154
Phytophthora spp.
Root rots,
blights
Vegetables, soybean, cowpea,
cocoa, citrus, tobacco
155
Pythium spp.
Damping off
diseases
Vegetables, soybean, cowpea,
common bean, chick pea
156
Rhizoctonia spp
Root rots,
blights
Vegetables, soybean, cowpea,
common bean, chick pea
156, 157
Sclerotium spp.
Collar rot,
southern
blight
Solanaceous crops, root and
tuber crops, legumes, rice,
Mucuna spp., Sesbania spp.
156, 158
Macrophomina
phaseolina
Black root rot
Soybean
157
Bacteria
Ralstonia solanacearum
Bacterial wilt
Tomato, pepper, eggplant,
groundnut
Xanthomonas campestris
Black rot
Kale, cabbage, broccoli
159
Agrobacterium
tumefaciens
Crown gall
Roses, grape vines, stone fruit
trees
Nematodes
Meloidogyne spp. (root-
knot nematodes)
Root knot
disease
Vegetables, legumes, tubers,
coffee, Sesbania spp.,
Tephrosia spp.
160
Pratylenchus spp. (lesion
nematodes)
Root lesion
disease
Cereal crops, root and tuber
crops, banana, coffee, tea,
Arachis spp., forage grasses
Crotalaria spp., Senna spp.
160
Radopholus similis
(burrowing nematodes)
Banana, citrus, pepper and
palms
160
in the nematode community structure by significantly increasing the
abundance of beneficial nematodes in the soil. An important consideration
is that all soils have an inherent natural level of disease-suppressive activity. In
most soils, long-term management, or lack thereof, can either reduce or
increase this level of suppression. A number of land-management factors such
as intensification in cropping, amending soils with organic matter, weed
management, and stubble retention have been shown to increase soil
suppressiveness to cereal root disease. The concept of a 'suppressive soil'
was first described by Menzies
131
to explain the phenomenon of soils that
suppressed Streptomyces potato scab. To date, natural suppressive soils have
been described containing a number of soil-borne pathogens such as
Gaeumannomyces graminis var. tritici (take-all disease of wheat), Fusarium
oxysporum (wilt diseases of tomato, radish, banana and others), Phytophthora
cinnamon
(root
rot
of
eucalyptus),
Pythium
spp.
and
Rhizoctonia
solani
