‘Econological’ reasons for choosing new plants
By Gary Jones
By Gary Jones
In the first Inside View column (which incidentally was this very same July issue back in 2007!) we discussed the many ways growers can keep up to date
In the first Inside View column (which incidentally was this very same July issue back in 2007!) we discussed the many ways growers can keep up to date with the introduction of new varieties and the wonderful smell of primroses in a small East Yorkshire seaside village.
Remember? No, of course you don’t.
In the March “Inside View” of but a few months ago, we reviewed the work Dr. Bill Snyder from Washington State University has been doing in looking at biodiversity of agricultural habitats to promote beneficial organisms in cropped areas (using Colorado beetle in potato crops as the model).
So, what’s the connection?
Well, Snyder was explaining that the increased diversity of species provided in organic systems produced more even-ness in the number of individuals across the various species.
It struck me that when it comes to selecting new cultivars, most of us are seeking new lines of the same crop species – different colours, fragrances or sizes of primrose flowers, for example. This does not generally create more biodiversity per se, although I suppose one could argue that different flower colours could add diversity to an ecosystem and affect insect attraction/repulsion to individual plants within a crop population
On some occasions when we’re looking at new cultivars, we find suitable new species. When this happens, it provides growers with a more diverse range of products to sell and in so doing reduces the risk or exposure to market instability. Increasing the number of species one sells not only has a direct benefit on the “crop ecology” and potential for naturally occurring biological control to be effective, but it also increases the grower’s “economic ecology” (should we call this by a new name, perhaps “Econocology”?) and with it (hopefully!) increased economic resilience.
To expand on this even further, perhaps we need to consider two other approaches already common to many organic farmers – that of “companion crops” and “allelopathy.”
Companion planting is the practice of planting different species together that are known to benefit one another. For example, members of the Apiaceae (or Umbelliferae, such as celery, carrot or parsley) family are known to be companion plants to many other species because their fragrant flowers attract beneficial insects to them and keep damaging pests away from other crop plants.
“Allelopathic” species are those that produce one or more biochemicals that influence the growth, survival and reproduction of other organisms in a negative sense. For example, lemon bottlebrush (Callistemon citrinus) and Lantana camara have claimed allelopathic properties on some crops, and Black Walnut (Juglans niger) is well known to suppress the growth of many plants unfortunate enough to find themselves within its canopy shade or rootzone influence, over and above those effects one might expect from simple competition.
The point is that when we’re seeking new cultivars or even new species of plants to include in our product range, we are often looking for very narrow criteria – flower colour, size, fragrance, fruit shape, shelf life, etc. Perhaps producers of ornamental crop species or greenhouse vegetables should consider looking to new species that might provide some wider ecological or economic resilience.
And another thing … perhaps we do not know the relative “companionship” (if that’s suitable terminology?) and/or allelopathic effects of the diverse range of bedding and potted plants that we throw together as bed partners (pun intended) in production greenhouses. How do we know the multitude of effects we may be inadvertently instigating or overlooking?
In closing, going back to Bill Snyder from Washington State, a snippet for your next pub quiz!
Did you know that the first thing a Colorado beetle does when it’s approached by a predator is to vomit on itself? Bizarre, yes! But given that the beetle enjoys a diet of potato leaves, and that those leaves are poisonous to most other creatures, covering itself in a layer of poisonous slime is probably not such a bad idea, albeit a rather unpleasant one. Short-term pain equals long-term gain – who knew? (Apart from Bill Snyder of course.) n
Gary Jones is co-chair of Horticulture at Kwantlen Polytechnic University, Langley, B.C. He serves on several industry committees and welcomes comments at Gary.Jones@kpu.ca.