Improving cover crop viability for pest control

As the biological product pipeline struggles to fill the gap created by the loss of nematicides, do growers have an alternative for nematode control? Cover crops could be the answer, but work remains to improve their viability and therefore boost appeal. In part two of this series, Dr Matthew Back, Reader in Nematology at Harper Adams University, explains ways that could further improve their effectiveness in nematode suppression.

“In my previous blog, we looked at four different ways in which cover crops behave to control nematodes, whether that’s by acting as a poor host, or by secreting suppressive compounds. The theory behind it all is excellent, but is really quite irrelevant if farmers are unable to unlock the benefits of these nematode-busting plants.

Instead, applied research can demonstrate how to improve the viability of cover crops for this application, and give farmers the valuable information they need for success.

Understanding the agronomy of the species

Just like a cash crop, cover crops come in many different species and cultivars, and with that, comes independent agronomic principles. This includes aspects such as nutrient levels, sowing dates and seed rates.

This doesn’t just have an impact on vigour or ‘yield’, it can also have an impact on the suppression mechanism of that specific cover crop. For example, research has shown that nutrients, in particular sulphur, impact upon glucosinolate production in brassicas grown for biofumigation. These react when incorporated into the soil, and release the toxic compounds needed for potato cyst nematode (PCN) control.

Another example relevant to biofumigation is the importance of equipment choice. For pulverisation, a simple flail is highly effective; for incorporation, deep mixing using a spader gives optimum pest control. The research team at Harper Adams University was able to work with AHDB to produce agronomic guidelines detailing all of this, which is an excellent way of translating research to farm level.

Physical characteristics

Aside from agronomic guidelines, there is distinct variation in characteristics of the different cover crops, drilling down through species and even variety. Some cover crops offer more biomass and root mass, whereas others are cold tolerant, which is useful for the UK climate.

Importantly, identifying cover crops that develop later in the season is important, to create a place for them within existing rotations. This is something that we are currently investigating as part of the DeCyst trap crop project, identifying which species has the greatest potential for commercial use.

Applied research in context

Herein lies the most important element of it all – making cover crops fit within existing crop rotations and production systems. They must be viable, as this will make them appealing and therefore increase adoption.

It’s important to consider the wider picture, so the cost of seed, labour, harvesting methods, to balance the inputs against outcome, and end value against need. Therefore, research needs to be applied and viewed within context.

Cover crops have huge potential to overcome a lot of challenges that growers face. They are far from a miracle cure, but used as part of an integrated pest management (IPM) programme, they could become a very efficient, cornerstone of cultural control. We look forward to contributing to the information and guidance currently available.

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Please note, the opinions expressed in this article are the author’s own and do not necessarily reflect the views or opinions of CHAP.