Greenhouse Canada

Growing Media Inputs
Do pests make growers invaluable?

August 11, 2016
By Gary Jones


September 2016 – Just recently, Dr. Tim O’Neil from ADAS in the U.K. spoke to Canadian growers on the topic of Root Mat Disorder (“Crazy Root,” as it’s called here). This has been seen on hydroponic cucumbers in the U.K. since 1993 and tomato crops throughout Europe (especially the Netherlands and France) a few years later.

Root mat has occurred in New Zealand, Japan and the U.S., and since 2013-14 in Russia1. It is now widespread in commercial vegetable greenhouses in Canada. Usual symptoms are an extreme proliferation of roots in the rockwool cube or slab (hence the name), potential to cause reduced fruit size and up to 15 per cent yield reduction. Probably more importantly, this disorder makes plants more susceptible to root rots such as Pythium.

Infection is typically early in the life of plants (within the first four weeks), with a plateau of infection being reached later and further infections less likely. Fast-forward two weeks and an event of a very different kind. The team at CubicFarm Systems Corp.™ launched their new system for urban agriculture production of leafy vegetables.


According to the website, “Due to the efficiency of our Cubic Farming system, one person working only a few hours a day will be able to plant, harvest, and deliver over 1,250 heads of lettuce per week to local grocery stores, restaurants, hotels, or wholesalers. Each CubicFarm machine has 160 growing trays that can produce over 2,500 heads of lettuce every two weeks or 5,000 basil plants every three weeks. Microgreens are ready in as little as one week.”2

A third news item of interest this week came from the Lower Mainland Horticultural Improvement Association (LMHIA), announcing the Fraser Valley Agricultural Pest (activities, gaps & priorities) Assessment Project. The announcement said that the LMHIA has successfully applied to the Investment Agriculture Foundation of British Columbia (IAF) to fund the project, the purposes of which are to:

Inventory recent and current activities, resources and projects (for both horticulture and livestock) devoted to pest surveillance, monitoring and management

Identify and assess gaps and priorities including current and emerging/future pest threats (including consideration of climate change impacts)

Bring producer organizations and relevant agencies together to confirm common objectives and next steps for co-operative action.

A couple of thoughts. Firstly, one Root Mat report states that “Increasing the biological
activity/complexity may help suppress the disease.”3 So, perhaps when it comes to pest control we have two options: excluding all possible organisms such as in the CubicFarm system, or building resilience by looking at pest management from a complete ecosystem viewpoint, as exemplified by recent work of Dr. Dave Gillespie at PARC, Agassiz.

Secondly, conversations at the CubicFarm launch tackled claims that “anyone could now be a farmer.” Sure, such systems are relatively simple to operate and can attract engineers or entrepreneurs to be primary producers in the larger food supply system, especially if pest and disease organisms can be kept out of the production units in the first place. But discussions around topics such as Root Mat Disorder or pest inventories are complex and multi-disciplinary, benefiting from additional background knowledge or experience. Maybe it’s better to develop engineering in a grower’s skills portfolio than to add plant pathology skills to those of an engineer.

Either way, though, more growers and more systems are probably going to benefit us all.

  1. Ignatov et al, “First Report of Rhizogenic Strains of Agrobacterium radiobacter Biovar 1 Causing Root Mat of Cucumber and Tomato in Russia”: ‘Plant Disease,’ 2016,
  3. O’Neill et al, HDC Protected Crops Report 241 (2009), “Protected hydroponic tomato: investigating the potential for various novel non-chemical techniques for the suppression or control of root-mat disease.”

Gary Jones is co-chair of horticulture at Kwantlen Polytechnic University, Langley, B.C. He serves on several industry committees and welcomes comments at

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