Shares in Plant Health Care accelerated their recovery from a seven-month low after the alternative agrichemicals group revealed initial endorsement for one of its key products by Germains Seed Technology.

Germains, the largest producer of sugar beet seed outside the seed giants, is to undertake "large-scale trials" in the US of Plant Health Care's Harpin product, after promising results from initial tests.

"Trials have shown excellent performance improvements," Paul Mullan, the Germains Seed Technology chief executive, said.

Besides supporting Plant Health Care's claims for Harpin, which designed to improve yields by boosting plant immune systems, Germains' decision will trigger a payment to the agrichemicals group.

A company spokeswoman declined to comment on the size of the so-called milestone payment.

'Very positive development'

John Brady, the Plant Health Care chief executive, said that the announcement of extra trials represented  a "very positive development".

He added: "While the milestone payment is welcome, of greater significance is that sugar beet can now be added to the list of important crops which respond favourably" to Harpin-based products.

The announcement follows the group's signing in 2010 of an initial deal with Germains, which is part of the Associated British Foods empire.

Plant Health Care shares, hurt last week when the group said that investors were being too optimistic on its outlook for revenues from joint ventures, stood 6.7% higher at 88p in lunchtime deals in London.