Weed out some nasty intruders

Saturday, June 16, 2012

Weeds can play havoc with vegetables, Kitty Scully reports

IF you ignore your vegetable plot for a week or two in June you may return to a multitude of minute critters ravishing your crops and chances are you will be facing an uphill struggle with weeds for the rest of the season. I appreciate that insects, big and small, are all god’s creatures and that some weeds are tasty, but I do actually enjoy bountiful vegetable harvests and prefer crunching homegrown carrots to chewing on chickweed salad.

What is a weed? A weed is simply a plant growing in the wrong place. Weeds or wild plants growing in a field, hedgerow or forest are all part of the natural vegetation, but if they grow too close to your vegetables they will compete for those essentials to good growth and bountiful yields: water, nutrients and light. Any cultivated plant can become a weed if it grows in the wrong place, like rogue potatoes popping up in your onion bed. Competition leads to lower yields and if left unattended, weeds can take hold and strangle your crop completely.

Weeds also harbour pests and diseases, which will spread to your crops, like flea beetle, carrot root fly and broad bean blackfly. Weeds cause a smothering effect and the lack of air circulation is the perfect breeding ground for fungal diseases such as mildew on onions. Weeds such as stinging nettles and prickly thistles also make harvesting rather unpleasant. It makes good garden sense to keep your crops weed free as it not only aids aesthetics but ensures plentiful yields.

Of course, weeds are not always our foe as many are medicinal and edible. Some are nutrient power-houses, tasty in salads or cooked like spinach and grow absolutely free, without cultivation. Wild plants have always been used for cures and in traditional medicine. Make sure to check a reference book before adding any weeds that you are unsure of to your plate as some are poisonous, such as groundsel, foxglove and nightshade.

There are plenty of ways of minimising weeds without nasty non-selective weedkillers. The main way to keep them under control is to pull them, hoe them, exclude light from them, eat them, or densely plant so they won’t have a chance to grow in the first place. Rotations certainly help and also the stale seedbed technique of preparing your seedbeds several weeks before you plan to sow your crops so weeds can be knocked back before your plants start. Planting through ground cover such as mypex or using organic mulches to block out light is also very effective.

It’s best advised to keep on top of weeds when they are young and the golden rule is, ‘one year’s seeding, seven year’s weeding’. The key point is not to let those weeds run to seed and spread their wares in multitudes. If so, they will haunt your harvests for years to come. Hoe, hoe, hoe.

June is the month when large colonies of aphids like to play havoc with your plants. There are a few different colours of aphids and they tend to affect a range of different vegetable crops. Blackfly or black bean aphid is the one that strikes your broadbeans and it can have devastating effects if not spotted in time. Blackfly tends to cluster at the top of plants and amongst the leaves and flowering buds. If the blackfly are in small quantities, squish them between your fingers to remove them from the plant. Observation is the key to good gardening as early detection is vital for controlling this fast multiplying pest.

Hosing your plants with water will temporarily remove them but this will need to be repeated and is not 100% effective. Washing or spraying the area with mild soap solution may help but will need to be repeated weekly. The most effective treatment is to pinch off the growing tip of leaves at the top of the plant as this is usually where the blackfly congregate in clusters. This does not damage the plant and will allow the plant to put more energy into swelling the beans. The best way to prevent this pernicious pest is to encourage natural predators such as ladybirds, lacewing larvae and hoverfly larvae into your garden. Growing host plants such as the poached egg plant, calendula and tansy also helps. More on companion planting next week. Home