Enough to Kill.....

Phylloxera..........?      

Phylloxera (Daktulosphaira vitifolia) is a small aphid-like insect native to north America. Phylloxera spread to Europe and then to many of the grape-growing regions around the world in the late 1800s.

Symptoms and damage

There are several types of phylloxera; those that affect the roots, those that affect the leaves and those that affect both the roots and the leaves.

The initial signs of a possible phylloxera infestation include a small area of weakened vines and showing premature yellowing in an otherwise healthy vineyard. By the time these symptoms show, the insect may have been present for 2-3 years, but at a level that is difficult to detect. The best time to look for phylloxera is when populations are likely to be at their peak during mid to late summer (November to March).

Phylloxera reproduces most successfully on healthy root systems; dead and weakened vines will often have low populations. When searching for a suspected phylloxera infestation in your vineyard, it's best to look for the pest at the border of the damaged area on vines just showing the first signs of decline.

One of the most important on-farm prevention measures is to exclude visitors, vehicles and other equipment from vineyard areas, unless appropriate disinfestation procedures have been observed or plant health certification provided. Signs at the property's entrance outlining the basic biosecurity requirements are helpful in reminding visitors and staff of their obligations.

On-farm prevention

Check that any grape plant, machinery, equipment or grape material from interstate is accompanied by appropriate certification. If a certificate is not provided with the item, don't allow it onto your property and report it to Biosecurity Queensland. Any equipment, machinery or footwear should have soil and vegetation removed before use in your vineyards.

By carefully digging up a number of roots within 50 cm of the soil surface, you can inspect new fleshy growth on fine, feeder roots for galls (small swellings), which result from phylloxera feeding. Root tips infested with phylloxera are often club-shaped or form hooks. Galls may initially be white or yellow, turning brown later. A 10X hand lens or greater will be needed to see the small (0.7 - 1.0 mm), oval-shaped, soft-bodied adults, which can vary in colour from green to brown or orange. A female can lay up to 400 eggs that, when newly deposited, are lemon-yellow, oval, and about twice as long as they are wide. Nymphs resemble adults except they are smaller.

Galls are formed when adult phylloxera lay their eggs into the leaf surface. Evidence of leaf galling may be found on both the upper and lower leaf surface.

                             

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Powdery mildew is caused by the fungus Erisiphe necator. It is endemic in Australia and one of the major fungal diseases infecting grapevines. The disease is characterised by white to ash-grey powdery fungal growth capable of infecting green vine tissue. Severe infection can lead to high crop losses and may also be detrimental to final wine quality. In Queensland, many of the commercial Vitis vinifera varieties are susceptible (particularly verdelho). 

Leaves
Yellow-green blotches (2-10 mm diameter) appear on leaves. Progresses to produce ash-grey to white powdery spores on upper and lower leaf surface. Often confused with downy mildew, which only produces spores on the lower surface of the leaf.

Berries
Produces ash-grey to white spores on immature berries and bunch stalks. Diseased berries may become distorted and split, causing them to shrivel or rot.

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