'Horticulture is a marathon, not a sprint'

March 10, 2014
Written by Gary Jones
Coincidentally reflecting the theme of this month’s issue of Greenhouse Canada, the Lower Mainland Horticultural Improvement Association (LMHIA) Growers Short Course at the Pacific Agriculture Show (held in Abbotsford, British Columbia at the end of January) brought together some wonderful speakers on a wide variety of topics, with many addressing energy, environmental controls and biological controls.

Indeed, of over 80 speaker presentations, almost 50 per cent (39 out of 81) were related to some aspect of pest management (if one includes diseases and weeds in the broad definition of “pests”).

On the technology front, Kevin de Kop from Priva NL described the third component of their new “TopCrop” system for crop management. Complementing the previously launched ventilation and heating modules, the new irrigation module completes the trilogy and is introduced as “a new plant-controlled concept for greenhouse process control.”

The hardware consists of three infrared cameras and three sensor boxes placed at strategic heights in a crop canopy (think of tall greenhouses growing vegetables or potted crops). These collect data on the greenhouse environment and plant water status, which when combined with the greenhouse environmental computer system completes the control of irrigation, heating and ventilation when the plants require it.

The system is based on crop activity, and Priva claims that “TopCrop provides a control for influencing the crop activity and the suppression of diseases.” So, the latest technology is helping towards disease control.

Two days later, in the morning session for organic producers, Marjolaine Dessureault of ES Cropconsult Ltd reported on trials of biofungicides to combat Sclerotinia, Botrytis and root rots on field beans.

Some of the now familiar biofungicides tested were Bacillus or Streptomyces products that required relatively high-tech development techniques. Other products tested were new plant extract formulations and while there were no statistically significant improvements using these products in this specific trial, there were large enough improvements seen to indicate that further investigation is worth doing.

In the same session, Dessureault’s colleague, Dr. Renee Prasad, discussed the work she’d been doing to control caterpillars infecting organically grown brassica crops in B.C. This is a problem, since many caterpillars are now resistant to Bacillus thuringiensis variety kurstaki (Bt.k., ‘Dipel’). Other suitable products may be harmful to beneficial enemies and relying on naturally occurring biocontrol agents to show up may not work because they may be too late or they might not have sufficient numbers to control a caterpillar outbreak in a cole crop.

Prasad and her colleagues are trialling a different species of B.t. (B.t. aizawai) to establish the necessary efficacy data for future label expansion after the product is approved. So far, results look promising and the work will continue.

Rounding off a morning session of organic talks, Dr. Bill Snyder from Washington State University described some research he’s been doing on increasing biodiversity in agricultural habitats to promote beneficial organisms in cropped areas.

Using Colorado beetle in potato crops as the model, he explained that when comparing conventional cropping systems with organic systems, he was surprised to find there was no difference in the number of taxonomical families or genera of beneficial species present.

Initially, this was discouraging, but biodiversity is measured in two ways: numbers present and “even-ness” of species present (i.e., is one species dominant, or are several species present in roughly equal numbers). When viewed from that perspective, Snyder found that organic systems produce much more “even-ness” of beneficial species present, and therefore are more likely to give better control of pest species.

Snyder mentioned that organic farmers who had been growing for a long time (more than 20 years) consistently report that aphids and caterpillars are no longer a problem in their crops, while farmers with younger organic farms still have to fight pest wars. Probably the long-term organic ecosystems are much more balanced and therefore have better built-in pest resiliency.

As one grower always tells my visiting class of students: “horticulture is a marathon, not a sprint.” Bill Snyder’s work gives validity to how some growers instinctively see how our most resilient production systems work.

Gary Jones is co-chair of Horticulture at Kwantlen Polytechnic University, Langley, B.C. He serves on several industry committees and welcomes comments at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Questions or comments? Email greenhouse@annexweb.com

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