There are 3 main reasons why pests come along. Let me greatly simplify the work of Dr Phillip S Callahan, John Kempf and Elaine Ingham:
Stress. Pests are attracted to plants for a variety of reasons, all of which can be traced back to a stress of some sorts e.g. poor soil (too dry, wet, compact), extreme weather, poor vigour, overfed plants, a plant that’s not in its happy place, or low plant diversity.
Overfeeding + artificial fertilisers. When plants are fed with artificial fertilisers, or overfed with anything – natural or otherwise, they run on simple carbohydrates, rather than complex carbs. What do pests eat? Simple carbs. Aha!
Lack of diversity. Plant health relies on diversity. Here’s the math: A diversity of plants + trees = a diversity of predatory and parasitic insects above ground + a diversity of beneficial soil biology below ground. This is the diversity trifecta – it’s oh so fertile, and a very low stress environment for plants.
The benefits of pests
Yes, tis true – a few pests here and there are no worries, they’re good even!
Firstly, they keep the predatory insects fed and hanging around, and secondly, they increase plant health. When a plant gets nibbled, chewed or sucked, it sends out a cocktail of compounds that make it less palatable. These same compounds increase vitamin/ mineral/ antioxidant levels within the plant – ain’t that something.
Large populations though, take their toll – impacting vigour, productivity and all round health. Great news is – they’re easy as to sidestep. Read on, dear gardener, part 2 will tell you how.
We’ve gotten so many things wildly wrong in the last 80 years of gardening, I can’t help but wonder if, as we learn more – it turns out that pests play as important a role as we now know fungi and weeds do.