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Orchard replant diseases focus at Interpoma

November 19, 2012  By Press release

November 19, 2012 – Replant diseases were the theme of the second day of The Apple in the World convention, held at Interpoma, the international apple industry trade fair held in Bolzano, Italy.

The first speakers were Robert Wiedmer, from the Alto Adige Consultancy Service for Fruit and Wine Growing, and Martin Thalheimer, from the Laimburg Research Centre for Agriculture and Forestry. They illustrated practical experiences and the results of tests carried out on land hit by fruit growing replant diseases in Alto Adige.

The speakers described the problem of exhaustion of cultivated land and then illustrated how the influence of tired soil on the growth of plants varies significantly from one area to another and often even in different areas of the same orchard.

Tests carried out by the researchers have revealed that chemical treatments of the soil have a significant affect on all the areas treated, while alternative measures have shown effective results only in specific circumstances.

The second speaker, Luisa Manici from the Agricultural Research Council (CRA/CIN) of Bologna, presented the results of tests on soil fungal communities as an indicator of soil health in fruit orchards.

Rot complex caused by fungi is the main biotic cause of the decline in yield that has characterized intensive cultivation systems in Europe. Manici explained that the average growth increase of plants on disinfected soils compared to replant soils is 42 per cent, as shown by a recent biological essay conducted on nine different apple orchards.

Root response to crop residues was the topic of Davide Neri’s – from the Università Politecnica delle Marche, Ancona – presentation while Mark Mazzola, from Washington State University, described some biologically-based strategies for the management of apple replant disease.

Gerhard Baab, from the DLR Kompetenzzentrum Gartenbau, described some experiences with replant diseases in apple orchards in Germany, and added that there are different causes, many of which have not yet been fully understood. According to Baab, who described some examples of treatments with organic products, dead roots and their residues probably cause an accumulation of bacteria and fungi that attack new roots.

Terence Robinson, from Cornell University, presented some examples of rootstock resistant to replant disease, such as fire blight. Robinson explained that the keys to the success of new apple orchard systems are the high density (about 3,000 trees per hectare) and the high yield – equal to about 150 tons per hectare – in the first five years.

In addition, he said, the system offers rapid growth of the plants, high yield of mature trees (more than 60 tons per hectare) and high quality fruit.

Finally, Walter Rass from the Alto Adige Consultancy Service for Fruit and Wine Growing, presented his research on a new machine that can exchange soil in the planting row. While the cost of the machine is still too high to make it economical, it has shown good results.

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