Agriculture Reference
In-Depth Information
Table 20.1.
The number of insect pest species recorded on the priority miombo fruit tree
species of Southern Africa.
Leaf- and
stem-damaging species
Fruit- and seed-
damaging species
Root-
Priority miombo
damaging
Sap-
Stem
Fruit-
Seed-
Total
fruit tree species
species
Defoliating
sucking
boring
feeding
feeding
species
Uapaca kirkiana
1
17
11
4
7
1
41
Parinari curatellifolia
1
14
4
?
3
1
23
Adansonia digitata
1
3
8
1
1
-
14
Strychnos cocculoides
-
-
1
-
-
-
1
Anisophyllea boehmii
-
1
-
-
-
-
1
Azanza garckeana
-
16
2
2
1
-
21
Flacourtia indica
-
5
4
-
-
-
9
Syzygium guineense
-
2
1
-
1
-
4
Syzygium cordatum
-
17
1
-
-
-
18
Uapaca nitida
-
2
-
-
-
-
2
Vangueria infausta
-
6
-
-
3
-
9
Annona senegalensis
-
6
1
-
5
-
12
Sclerocarya birrea
-
25
5
16
5
-
51
-, records not available.
P. curatellifolia
subsp.
mobola
,
Uapaca kirkiana
and
U. nitida
are reported to be
susceptible to
Armillaria
root rot in Zambia (Parker, 1978) and in Malawi (Lee,
1970).
Armillaria
consists of several species, which may differ in host range as
well as in pathogenicity (Strouts and Winter 1994). The fungus kills the inner
bark and cambium and later invades the wood. The tree will die as a result of
girdling at the root collar or extensive root killing.
Armillaria
is a potential threat
to proposed orchards of wild fruit, particularly where miombo woodlands have
been cleared to provide plantation sites (Parker, 1978). The reason is that
Armillaria
species affect many species in the indigenous forest. For instance, in
Zimbabwe they are endemic in miombo forests.
Other root and butt rot fungi such as
Fomes
and
Ganoderma
spp. develop
their fruit-bodies, called brackets, close to the stem base or on roots (Parker,
1978).
Ganoderma lucidum
affects
Parinari curatellifolia
in Zimbabwe (Masuka
et al
., 1998). These fungi probably infect roots by means of airborne spores
washed into the soil. A different type of root rot is caused by
Phytophthora
spp., also attacking seedlings in the nursery and causing rot of succulent roots.
In affected trees many small roots die and necrotic brown lesions in the inner
bark are often present on the larger roots and in the lower trunk. Trees suffering
from such root rots often begin showing symptoms of drought, and become
weakened and susceptible to attack by other pathogens or various other causes
that are then mistakenly taken as the causes of the death of the tree. These
fungi grow and produce spores under moist soil conditions, and as the spores
disperse with the soil water the roots of susceptible hosts will be infected.
Losses caused by
Phytophthora
are great on fruit trees, especially in soils with
bad water drainage. There is a dearth of quantitative data on the losses caused
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