Cultivation of grapevine in tropical
area, like in Indonesia, posses several problem. With high rainfall and high
humidity, and without cold period to overwinter pathogen, disease always
present all year round. One of the diseases here is grapevine leaf rust, caused
by specific fungus that attack grapevine leaf.
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Example
of grapevine leaf rust.
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Grapevine leaf rust usually occurred
on monsoon season, with period of high rainfall and warm temperature, can cause
this disease to grow and thrive on grapevine leaf. Especially on vineyard, that
using too close planting space between vine.
Main symptoms of this disease is,
there are many small yellowish spots, on upper leaves surface, and will turn to
brown after few days. At under leaves surface, there are many orange dots or
spots, that if touched, it will feel like a dust. This orange dusts are spores
of fungus, that cause this disease.
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Under
leaf surface of grapevine, Physopella ampelopsidis, spores seen.
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From many sources, this disease,
caused by fungus Physopella ampelopsidis(Diet. Et. P.
Syd.), others name is Physopella vitis
(Thum.). (Semangun,1989).
Control of this disease are with,
removal of infected leaves, that marked with yellow or brown spots, and using
chemical methods, fungicides spraying.
On my experiences, sprayed with
contact fungicide, like Dithane M-45 with active ingredient of mancozeb, with
dosage of 2-3 grams per liter of water, have good control efficacy.
Another contact fungicides like
Daconil can also be used, with active ingredient of chlorothalonil, with a
dosages of 1-2 gram per liter water mixture, also effective in controlling of
this disease.
Routine spray with contact fungicide
is a must, at least once a week, because this diseases usually occur on monsoon
or rainy seasons, where high rainfall can wash fungicides coat away from
grapevine leaves. Adding surfactant and sticker also helpful on monsoon
seasons.
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Grapevine
leaves, that lightly infected.
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Systemic fungicides like AmistarTop
with active ingredients of Azoxystrobin and Difenoconazole, with dosage of 1ml
per liter, are the most effective means of chemical control this disease,
because this fungicide is systemic, it’s mean, that plant will absorb it, so it
will have long lasting control and efficacy compared to others contact
fungicides. Also systemic fungicides, will not easily wash away by rain like
other leaf coated contact fungicides.
But the usage of this kind of
fungicides, need to be rotated with another fungicides, to minimize the risk of
pathogen resistance against fungicides.
Also, at monsoon or rainy seasons,
vineyard must be clean, especially on soil beneath grapevine, weeds need to be
removed, prior to rainy seasons, any other grapevine debris must also be
removed and burned to prevent spreading of diseases.
Fertilizing grapevine with
fertilizer that contain potassium will reduce the incidence of infection of
this grapevine leaf rust disease.
Semangun (1989), Penyakit-Penyakit
Tanaman Hortikultura di Indonesia. Gajah Mada University Press, 850 hlm.
