DiseasesCitrus greening disease
This disease causes sectorial yellowing of leaves. Fruits
are small and
lopsided. Tree
may blossom out
of season. It is
transmitted by
citrus pysllid.
Control• Control psyllids with insecticides.
• Plant seedlings from certifi ed nurseries.
• Rogue infected trees and disinfect budding tools
from one seedling to the next.
Citrus gummosis
Bark rots on the roots or the trunk and the branches. In
early stages of infections gum oozes from the infected
parts hence the name gummosis. Leaves start yellowing
and the twigs dieback and the tree eventually dries up
and die if untreated.
Control• Surgically remove the bark or burn it with blue fl ame
from a propane torch.
• Fertilize and irrigate the treated trees.
• Use tolerant rootstocks - Cleopatra mandarin.
• Weed from the tree trunk outwards.
• Avoid planting on heavy or waterlogged soils.
• Plant seedling with the bud union at least 6cm above
the ground level.
Management of citrus pests and
diseases
Kenya Agricultural Research InstituteP.O. Box 57811-00200, NAIROBI.
Tel: 254-20-4183301-20, Fax: 254-20-4183344Email: [email protected]
Website: www. kari.org
Compiled by: Kega, V.M.
For more information contact:
Centre Director, KARI Katumani, P.O. Box 340- 90100, Machakos
Tel: +254 44 20495, 20395/8, 21638, 20422Fax: +254 44 21122
Email: [email protected]
KARI information Brochure series / 16 /2008 Ksh. 20
Citrus greening disease symptoms
They produce a lot of honey dew leading to black sooty
mould development which eventually leads to twig
dieback and loss of fruits.
Control• Ring-band the tree trunk with insecticide to
discourage climbing attendant ants.
• Spot spray the heavily infested trees or alternate
rows paying attention to the underside of the leaves.
• Prune off heavily infested branches.
Citrus black fl y
These appear as colonies of black small insects on the
underside of leaves. A thin fi lm of wax covers them.
Control • A parasitic wasp normally keeps these pests in check.
In severe infestations sprays of contact or systemic
insecticides are effective.
Citrus soft scales
These are small motionless insects mostly found on the
young and succulent tissue on leaves, stems and also on
fruits.
Control• Ring band the trees
with anti-climbant
insecticide. This
discourages the
attendant ants from
climbing and attending the scale.
• Spray with mineral oil.
Russet mites
These attack the fruits resulting in silverfi sh colour
Bud mites
They attack the young buds and shoots resulting in
whitish to silverish small spots on leaves causing severe
malformation of leaves and spread to new growth.
Control• Avoid dusty conditions by siting orchards away from
roads.
• Plant wind breaks and in heavy infestations spray
with acaricides.
IntroductionCitrus yields are often low and fruits are of poor quality
due to pests and diseases. Information on common
pests and diseases and their management is important
for improved yields.
PestsMediterranean fruit fl y
These are brightly coloured fl ies that lay their eggs on
citrus fruits. The fruits develop spots and change colour
to orange or yellow when still immature and eventually
drop from the tree.
Control• Spray alternative rows with systemic insecticide and
insecticide baits.
• Systemic insecticides in honey or fermented juice are
also effective.
Citrus woolly aphid
These are small insects covered with curly white wool
hence the name woolly aphid.
Mediterranean fruit fl y
Woolly aphid on leaf
Russet mites on fruit
Citrus soft scales on leaf