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| Authors: | G.S. Brown, L. Koutoulis |
| Keywords: | ARD, methyl bromide, dazomet, calcium, lime, trichoderma, mycorrhiza, nematode, nematicide, MAP |
Abstract:
After extensive glasshouse trials, a set of potential treatments to improve tree performance in soils with apple replant disease was identified and a field trial established in 1999. After the first season it was found that methyl bromide soil treatment provided superior tree growth, while trees growing in soil treated with Dazomet or nematicide plus Mono Ammonium Phosphate (MAP), grew as well as some of the methyl bromide treatments.
Nematicide plus calcium hydroxide, nematicide plus trichoderma and nematicide alone gave a poor growth response, which was slightly greater than untreated soil.
The following treatment rating was developed: 1) Methyl bromide, 2) Dazomet and nematicide mixed with MAP, 3) All remaining nematicide treatments, and 4) Untreated soils.
Over the subsequent seven years mature yields of over 80 tonnes/ha/year were achieved by the third cropping season.
Based on cumulative yield for the first five years of cropping it was found that methyl bromide, Dazomet and calcium hydroxide treatments had similar yields, between 275 and 310 tonnes ha-1. The remaining treatments yielded significantly less fruit, from 228 to 248 tonnes ha-1, not different to the trees growing in untreated soil at 215 tonnes ha-1. Hence, after 5 years of fruit production the following treatment rating was developed: 1) Methyl bromide, Dazomet and calcium hydroxide, 2) All remaining treatments and the untreated soils.
MAP treatment, considered a good treatment after the first season, yielded the least fruit (228 t ha-1) of any of the treatments while the calcium hydroxide treatment, considered poor after the first season of growth had an excellent cumulative yield.
This highlights the need to study long term tree performance in apple replant field trials.
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