Hi their, My Grape leaves tree start having white spot what should i do please and thank you
Thank you for contacting Toronto Master Gardeners.
Your question is about a Grape Tree. A photo of the grape tree and closeup of the leaves would help to access their condition. Most grapes grow on woody perennial vines. Grape vines are susceptible to many kinds of disease including Powdery Mildew which is the fungus Uncinula necator. White spots begin on the underside of the leaves and progress to large white spots and areas on the top of leaves. The leaves may become brittle and drop off. This may be what you have.
Cultural conditions which encourage re-occurrence of Powdery Mildew fungus are fruit and leaves left on the ground in winter. This fungus can also be present in old canes and bark. In the spring, during prolonged wet periods, spores infect plant tissue. In mild early summer weather, disease can spread throughout the plant, particularly in shaded, sheltered areas.
Preventive measures include removing dense branches to increase air flow and light to the plants. Irrigate with a drip system that provides adequate irrigation to bottom of plants. Too much water on leaves and soil surrounding plants will encourage fungal growth.
Most importantly, choose grape varieties that are less susceptible to mildew. Suggested treatments with different fungicides and preventive treatments for powdery mildew can be found at the link below:
Hope your grape leaves improve with the suggestions above. If this does not look like what you are seeing, please send us a picture that will help diagnose the issue.