The month of March is named after Mars – the roman god of war. Apparently because the narrow passes of the Alps began to thaw at this time of the year, becoming passable again and so the Roman legions could go back out to conquer new territories or send reinforcements to older ones. There actually might be something more universal in that ‘March action’ mind-set , as the ancient Irish Fianna (the warrior class) would happily rest up all winter and then start back training and regular hunting come the green shoots of this time of year.
It is a timely reminder that March thaws also bring the beginning of pest season. So maybe its the right time to take a deep breath and go to war.
Vine weevil (Otiorhynchus sulcatus) is an enemy in two parts or more to the point two stages: the young aka the grubs will eat the roots of ornamental plants and many fruiting bushes and strawberry patches, while the adults are voracious pests – munching unsightly notches out of leaf margins. The adults will be emerging soon and will stay active eating and lying until summer. Some years the grubs continue to inflict unnoticed damage over the entirety of a mild winter – and those plants that appear dormant but you anticipate are ready to spring back to life are possibly rootless and dead and will not be burgeoning on schedule.
Sticky traps really work on the adults; you can get garden centre tap traps but those same one to keep flies out of the kitchen or greenhouse work a treat, simply mount on a stick and put it near infected plant. For the grubs, it’s to enlist the help of a biological control agent, not mustard gas or novichok but some simple pathogenic nematodes (Steinernema spp being the most popular). These grub-killing machines come in a sachet and are added to a watering can and delivered to areas of need in minutes. Best time to deploy is autumn. There are also adult-attacking nematodes available in local garden centres.
Slugs and snails (various species) – the old enemy, but the old tactic of slug pellets is not best practice if you like wildlife and want to be more organic. I know there are organic pellets available but beer traps do work and so does a sachet of mollusc-infecting nematodes (Phasmarhabditis hermaphrodita) too. Harsh grit around prize plants is too rough for them to crawl over; the eggshells only get washed away. Personally I never had much success with copper wire or the other barrier methods. Slugs and snails are active all year, they mostly work at night but we often think they are hibernating for winter, they are not really, it’s just a diminished food supply. Now that you are back sowing and planting, they can sniff out the feast and will soon gate crash the party.
Aphids (various species) are another perennial pest and as good as year round enemies in mild years, if you have a polytunnel or green house. The garden variety is readying now. They don’t just suck all the sap from our seedlings and plants but they also potentially transmit virus disease as they go from plant to plant. Those yellow traps will lure many to a sticky end of slow starvation but I find you can’t beat a good drowning in garlic spray. The garlic is toxic to them. The old trick of sudsy water was effective because it formed bubbles over their breathing holes and they suffocated. The garlic is a bit more humane but also higher success rate. Plus who knows exactly what chemicals are in the washing up liquid, hand soap or horti-soap to be absorbed by your edible plants and later by you. You can also wipe/squish them off between finger and thumb or encourage ladybirds that individually eat around 5000 aphids per year.
Allium Leaf Miners (Phytomyza gymnostoma) are prepping for a first emerging generation right now and they will soon be laying into onions, garlic, shallots, chives and leeks. The maggot will burrow in deeper and feed off the insides of your crop, triggering rot. There currently is no commercial sprays, organic or otherwise on the market. And the normally reliable garlic won’t work on a pest that feeds off garlic. The best line of defence is to cover standing crops with horticultural fleece or a protective fine-mesh netting now. Crop rotation and planting out later is beneficial to stay ahead or out of reach of the soil wintering generation and the fly overs.
Top tip Expand your army: if your garden is more bio diverse then all of these pests are eaten in vast numbers. A few wild flowers and shaggy patches will entreat new recruits but also build some billets for the troops. Rove beetles and hedgehogs will appreciate an over wintering log pile, frogs and toads will be grateful for a wildlife pond or barrel and birds will take up the opportunity of a nest boxes or perchable cover – that’s as simple as a tree or hedge. A small but unkempt corner of nettles will do the ladybirds.