Powdery mildew is one of the last diseases
The fungus that infects grapevines, which causes
Heavy losses in the grape crop:
The fungus that causes powdery mildew in grapes.
Powdery mildew disease in grapes is
considered one of the most dangerous
diseases of grapevines; where it is damaged
Trees and fruits are very dangerous.
The spread of the disease begins during the end of April and until
Powdery mildew disease affects most grape varieties
This is due to the delay in its maturity until the time when it is
The air temperature is also high, and the humidity is high, which helps the spread of disease.
As for the early ripening varieties, they survive
From injury, such as the cultivars of Alsprior and Alerali grapes
Asprior and the film Siddles and the girls Thompson Siddles.
Symptoms of powdery mildew in grapes
Symptoms of powdery mildew appear
On all parts of the grape trees, whether the leaves
the tender twigs, flowers and fruits; in different
phases of its formation
First: Symptoms on the papers:
Fine white to gray spots appear on the leaves
Appearance on the upper surface or the lower surface or
both surfaces together; Could it be more clear?
the top surface of the paper; These spots extend under the appropriate conditions until they cover the entire surface of the leaf
Leaves also tend to twist upwards, especially in
Hot weather and as the infection progresses, the leaves turn in color
to a brown color as a result of tissue death; then wither
Leaves dry up and then fall off.
Symptoms powdery mildew on branches.
The infection appears on the tendrils and tender branches where
It shortens in length, then takes on brown, then black
Then they dry up and die as the infection progresses.
Symptoms of infection with powdery mildew on flowers and fruits
Flowers and fruits are also subject to infection
The flower clusters wither and are unable to hold the fruits.
But if the fruits are infected while they are in an advanced stage, they are
It grows irregularly, dries up and takes an unnatural color
It can crack and not ripen; And when the injury intensified
It smells like rotten fish.
Conditions suitable for infection with powdery mildew in grapes:
Powdery mildew is caused by grapes
This is when the air humidity rises to 80%.
The temperature reaches 25 degrees Celsius.
Resistance to powdery mildew in grapes:
Control of powdery mildew.
1- Good pruning that allows air to enter
And the sun to the heart of the trees.
2- Removing the basal leaves on the rootstock
for trees; As it has an effective role in reducing infection
3- Take care of potassium fertilization, as it has an effective role
In reducing and limiting injury.
4- Using growth regulators as they have an effective role
in disease resistance.
5- Use of Gibberellic acidafter pruning, because it encourages
Buds open early, which leads to early harvest.
Thus, he escapes from infection with powdery mildew
6 – Follow-up to the weather forecast to determine the timing of spraying
Suitable for the prevention of powdery mildew disease
biological control powdery mildew.
Where it must be sprayed with the biological compound, using
The biological compound
Ampelomyces Quisgualis ( A Q 10 )
And that at a concentration of 5 g per 100 liters of water; And that’s after the buds open and the new vegetative growths reach a length
10-15 cm, at a rate of one spray every 15 days; and stops
The number of sprays on the cultivated variety.
Third: Chemical resistance:
Chemical resistance must be done first
Before infection occurs, using an antiseptic
fungal like micronized sulfur or sorrel 80%
Or thiophite, karathine, or micronite.
Spraying is carried out using micronized sulfur at a concentration
250 g per 100 liters of water sprayed on wood at
bulging buds; Where. Germs are eliminated
latent in the scales of the buds; Also, sulfur
Eliminates spiders lurking in the buds.
And the spraying is repeated again, after the buds open and the arrival of
New vegetative growths to a length of 10-15 cm
What if the infection appears on the trees?
It is sprayed with one of the pesticides in
The focus of infection and of these pesticides.
chlorothalonil, horticultural oil, potassium bicarbonate, and Bacillus subtilis
Note that a publication must be added
It should be sprayed early in the morning
It should not be sprayed at high temperatures
30 degrees Celsius.