Orchard soil management

Soil treatments for Apple Replant Disease (part 3)

Biological treatments vs chemical treatments: It is interesting to note that there was a big difference between the two biofumigants after the second leaf, but at third leaf there is now little difference between these two in shoot length and number of shoots.

Biological treatments vs chemical treatments (cont from last issue)
The tree diameter is, however, 10mm less under the cabbage and mustard biofumigant treatment. The cabbage and mustard also had the least apples per tree and the highest root lesion nematode population after planting.
Trial highlights
Apple replant disease is a complex interaction of the soil-borne nematodes, fungi, bacteria and microfauna that build up in the soil as a result of continuous planting of apple trees in the same area, slowing root growth and function, and negatively affecting tree growth, vigour and productivity.
The trial has highlighted that growers have good chemical and non-chemical options available to them, with both chloropicrin and the beneficial bacteria performing well, showing impressive growth in stem elongation, trunk diameter and yield.
Access to alternative biological treatment methods for apple replant disease is important due to the uncertainties around the future availability and acceptability of some chemical treatments, and their environmental impacts.
Adding beneficial bacteria onto the roots enabling the trees to unlock more of the nutrients in the soil and improve the tree growth and therefore the yield has performed very well in this trial and this biological treatment offers an effective chemical-free method of treating sites that are prone to apple replant disease.
Since this trial has been undertaken, treating old apple ground with chloropicrin has now become more widely used in WA apple orchards, as the benefits of improved growth rates and yield are now more widely understood.

See this article in Tree Fruit Jan 2021

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