Tuesday, February 22, 2011

Botrytis and Berry Splitting - UPDATE 22/2/2011

Since the weekend we have been busy monitoring for weather damage in vineyards.

High rainfall events during ripening commonly causes the skin of grape berries to split - fortunately it seems damage has been limited with most vineyards escaping with minimal splitting. Typically less than 1% damage has been seen.

Riesling, Chenin Blanc, Pinot Gris and Sauvignon Blanc are the main concern where some botrytis has been seen to develop in the last 72 hours (above). We have also seen one vineyard of Shiraz in Blewitt Springs and one vineyard of Grenache that is developing botrytis bunch rot.

Thursday, February 10, 2011

Conventional vs Organic Late Season Botryticides

Botrytis risk is most severe where excessive nitrogen has been used, where air circulation is poor, or where apple moth or other factors have damaged bunches. Rotted berries typically have a gray cast of the mycelium and spore-bearing structures present which gives the disease its common name - Grey Rot.

Conventional Late Season Fungicides

Dicarboximides - Rovral, Chief, Corvette etc should be applied as an acidic spray tank mix (water pH less than 7) to be stable. 1kg/1000lts of tartaric acid, citric acid or similar, or a commercial buffer- tradenames include AGRI-BUFFER will acidify the water and lower pH.

PMS - (Potassium metabisulphite) dries out the bunch and can help heal berry splitting. PMS rates higher than 3kg per 1000 litres are needed and the pH of the spray solution should be adjusted to between 2.9 and 3.0 using 1.5 kg 100% tartaric acid per 1000L.

Organic Botryticides Options.

Information for control of late season Botrytis in Vineyards is difficult to get reliable, scientific trial results on.

Peratec® is a formulation of peracetic acid and hydrogen peroxide. It may work as a broad spectrum surface sterilant. If you are in a tough situation it maybe a valid option, but note the following; Peratec® can be difficult product to find in retailer stores. It is recommended that this product is pre-ordered and stocked in your chemical store for use as weather requires.

Wednesday, February 2, 2011

Snakeoil or saviour? - Q&A

How do you tell the value of alternative fertilizer products?

Over the last few seasons, especially during droughts and heatwaves, the farmers that use biological principles – like increasing soil health and soil life – are seeing results. We are focusing on using biological products on a widescale and helping bringing a focus on soil health into mainstream farming practices.

But how do you tell snake oil from genuine product?

Every year many products circulate the market claiming to replace commercial fertilizers, to make nutrients in the soil more available, to cost less than traditional fertilizers, to supply micronutrients, or to be a natural product. While some of the claims may be true, more often they are not, or at best are partially true.

The types of products being advertised can be broadly assigned to three categories: soil activators, wetting agents or surfactants, and soil conditioners. Some products are said to introduce beneficial organisms or to stimulate existing soil microbes. While these so-called soil activators might increase microbial activity, their effect compared to what is already present in the soil can be considered a drop in the bucket that does not translate into improved yield.

Products sold as wetting agents or surfactants are successfully used to improve the surface coverage of insecticides and herbicides by reducing water surface tension. However, there is not as much independent evidence for using such products to improve water infiltration and retention in the soil or to loosen compacted soils.
Products advertised as soil conditioners are designed to improve the physical condition of the soil and thus enhance aeration, root growth, and water retention. The typical products in this category contain humates and humic acid, or some other type of organic material mixed with inorganic elements such as rock phosphate, limestone, or some other mined mineral that has been ground.

The best approach with new products is caution. If the product is being advertised to make nutrients more available in the soil, ask yourself, if the product increases the availability of a particular nutrient, how can it increase yields (as is being advertised) in a field where that nutrient is already present in adequate amounts? Other points to consider are: Do I have problems with this nutrient on my farm? Have I seen micronutrient deficiencies there? More often than not you will find that you do not need the product, and if you discover that you are lacking in a particular nutrient it is better to invest in products that have been proven through time.

People promoting new products are well versed in selling techniques and can be very persuasive. If you become convinced that you really need a given product, or you are simply curious to find out how well it works, take a conservative approach. Apply it only on an experimental basis so you can be your own judge. Trial work is the key to really assessing the value of what you apply.

For more information contact; james@djsgrowers.com.au