Published Date: 2010-12-24 11:00:04
Subject: PRO/PL> Sooty mould, mango - Tanzania
Archive Number: 20101224.4528
SOOTY MOULD, MANGO - TANZANIA
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: 23 Dec 2010
Source: FreshPlaza [edited]
Mango production, now at 300 000 tonnes a year, is threatened by
sooty mold disease, which attacks the leaves. Dr Delphina Mamiro,
Sokoine University of Agriculture, noted that the disease slowed
plant growth and reduced fruit production causing heavy losses.
The scientist pointed out that the threat was serious for farmers
because the majority do not have enough funds or the knowledge to
deal with the disease. She called on the government, donors and other
stakeholders to assist in fighting the disease by allocating more
funds for research and to educate the producers on the ways of
controlling the disease. "The foliage may turn yellow. Sooty mold is
a monophyletic group of fungi living on leaves and stems of plants
characterised by dark pigmented hyphae that grow on the leaf
surface," she said. The accumulation of fungal mat on the leaf
surface does not cause physical lesions, but has the potential to
reduce sunlight penetration and suppress photosynthesis.
According to Mamiro, the disease is found infecting various plants,
forming dense, sometimes spongy coverings. She said a survey at SUA
indicates that guava, avocado, lemon, pummelos, sweet orange, lime
and mango have been affected by the disease.
She said sooty mold growth can be reduced by limiting sucking insects
and controlling the insects that cause honeydew to coat plants.
"Insects can be controlled with a variety of integrated pest
management tactics," she noted.
[Sooty moulds are saprophytes which live on the host's surface. They
are not pathogens in the true sense because they do not invade the
plant tissue, but are secondary invaders. They follow different pests
(for example, scale insects or aphids) excreting honeydew which coats
the plant and provides a growth substrate for the fungi. They occur
on a range of hosts including many fruit trees, shrubs and
ornamentals. On mango, species of several genera (for example
_Capnodium_, _Meliola_, _Tripospermum_) are known to occur.
Plants become blackened with velvety fungal growth and are usually
sticky. The whole plant may be affected, and the moulds are difficult
to remove. They reduce plant vigour and productivity by restricting
the light available to the host for photosynthesis. The moulds may
also grow on plants not affected by insects if honeydew drips from
overhanging vegetation. They are more likely to grow in dry
conditions as rain washes the honeydew away.
Disease management mainly focuses on control of the insects and may
involve pesticides, soap or oil-based organic sprays, or biological
control by specific predator insects.
Map of Tanzania:
Sooty mould on mango leaves:
Young mango tree with scale insects and sooty mould:
Sooty mould on citrus fruit:
Information on sooty mould on mango via:
Sooty moulds on various species:
Main sooty mould species found on mango via:
Fungal taxonomy via: