What if there was a way conventional greenhouse growers could avoid the cost of multiple curative measures by simply preventing losses from pests and diseases in the first place?

By James MacPhail

Unlike soils which contain a plethora of plant-friendly biology that can help reduce the damage done by pests and diseases, growing substrates such as coir and rockwool are usually sterile, and why not?

Conventional growers have a veritable arsenal of tools to fight off pests and diseases whenever they attack throughout the season. But often chemical treatments for one thing can leave plants vulnerable to others, which can result in a snowball of everlasting treatments for this and then that.

Organic growers might not have the same number of weapons at hand, but rarely do problems like this obstruct human ingenuity for long. Their approach: simply prevent losses at the beginning of the season, rather than cure disease later on.

With many European growers operating both organic and conventional growing systems, we’re seeing more and more cross-pollination of techniques, particularly from organic to conventional. In short, conventional growers are catching on to the importance of biologically active substrates, and the opportunity they present to rely less, and therefore spend less, on curative measures.

Preventing losses is no mean feat however. Plant-friendly symbiotes such as Mycorrhizae and Trichoderma are effective in improving plant health and vitality because they out-compete soil-borne diseases and strengthen plants’ own defence systems, but the issue remains that neither Mycorrhizae or Trichoderma are particularly recalcitrant, and can be easily washed away when artificially applied in controlled growing systems.

That’s where things get a little creative. By housing the fungi in biochar, and then mixing the biochar with rockwool or coir substrates, conventional growers can create a biologically active growing environment that will see greener leaves, healthier plants and higher yields all season long.

But how exactly does this work?

Biochar is a type of charcoal made from woody waste, cooked at a low temperature over a long period of time with minimal oxygen. This process leaves it highly porous. When applied to soil, rockwool or coir it improves water holding capacity, increases nutrient delivery to plant roots and provides a permanent housing for beneficial soil micro-organisms, including Mycorrhizal and Trichoderma fungi.

Our biochar products are readily enriched with Mycorrhizal and Trichoderma fungi, and a simple scoop of it into a slab of rockwool or coir at the beginning of the season is enough to visibly improve the health and vitality of crops.

Our enriched biochar products have on average resulted in an 15% increase in yield in customer trials over 35 hectares in nine European countries, despite the presence of pests and diseases including nematodes, pythium ultimum, armillaria mellea, phellinus noxius, rhizoctonia solani and armillaria ostoyae.

An example of this is a UK grower trialling our products on tomatoes grown in rockwool where there were issues of radiobacter. The trial, carried out on a 2000 metre block, netted an 11% increase in yield.

Research & Development is the only way growers can get an edge on the competition, and sometimes it’s as simple as paying attention to what other growers and other growing systems are doing. Take a big, healthy leaf out of the organic book and let there be life in your once sterile substrates.

James MacPhail is the Commercial Director of Carbon Gold, a UK based manufacturer of Enriched Biochar solutions for horticulture. james@carbongold.com