OFF TO A GOOD START WITH MYCORRHIZA, by Liz Copas

Apples, like most trees and shrubs, live in close association below ground with a host of bacteria and fungi. Many of these, called mycorrhiza, are extremely beneficial and form a symbiotic relationship with the roots of plants. They rely on their tree host’s roots to supply them with carbohydrates and in return, facilitate the uptake of phosphates from the soil into the roots, an essential element for healthy root growth. This mechanism is especially beneficial when soil phosphate is not readily available in some soil types. In conditions that are less than perfect or soils with a SARD problem the mycorrhizae grow slowly and the relationship takes longer to build up. Without this mutual assistance, roots will take time to establish and tree growth will be slow. This is where an addition of mycorrhiza at planting time can be very beneficial.

In an NACM trial some time ago, Katy trees needed replanting in an orchard where there were some losses from wet feet or crown rot. They were all dipped in fungicide [a treatment no longer approved] before planting and half were given a small quantity of pelleted mycorrhiza into the planting hole. Our results were encouraging. There was a prolonged period of drought shortly after the trees were planted but the treated trees survived with only moderate stress symptoms compared with the cupped and scorched leaves of the control trees. By the end of the first year the treated trees were healthy, more compact and full of flower bud, a useful result for Katy. The following spring they flowered precociously and set more fruit than their neighbours, all signs that the root systems had got off to a good start and established the trees well to cope with the difficult conditions.

There may be little benefit from the treatment when planting into good or excellent soil conditions. But should you have a possible replant problem, SARD or a soil where phosphate may not be readily available for uptake, mycorrhizal addition at planting time may be a useful action. There are several products available, some come as pellets and some come as a dip with incorporated hydrophilic gel to enhance the adhesion of the fungi to the roots. Try http://www.symbio.co.uk for further product information

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