Vine Diseases and Compost Tea
The main diseases that can effect vines during the growing season are Powdery Mildew, Downy Mildew and Botrytis. Downy Mildew has unfortunately arrived at Albury!
Downy Mildew is a white down that appears on the underside of the leaves causing them to wither and die, the fruit can also be attacked. The standard treatment in an organic vineyard is a copper solution.
As the name suggests Powdery Mildew appears as a white powder on the leaves and grapes. If left untreated the leaves die and the fruit will crack. Dusting or spraying with Sulphur once every 2 to 3 weeks can prevent this disease.
Botrytis will cause fruit to rot and drop off the vine and dark patches will be seen on the canes. This usually appears during Autumn when the fruit is ripening. Avoiding overcrowding of the vines and keeping the bunches well ventilated by removing the adjacent leaves will help restrict this disease.
During last week Downey Mildew has started to appear on some of the leaves at the vineyard, mainly on the Chardonnay. This isn't serious at this stage but we have decided to spray the vines with a copper solution to try and stop it from spreading.
Next year we hope to avoid copper and sulphur by using a compost tea. This is a water extract of compost that is "brewed" to extract organisms (bacteria, fungi, protozoa and nematodes). When sprayed on the vines an enormous diversity of these organisms dominate the surfaces of the vines thereby inhibiting disease-causing organisms from establishing. Compost tea also provides plant food which aids healthy plant growth, strengthens the plant's defence systems and, with the addition of beneficial organisms to the soil, will help the recycling of organic matter improving soil structure.