Watch out for the slugs as they will be out in full force, especially after a shower of rain – use an organic slug pellet, that is one containing ferric phosphate, rather than metaldehyde, Advanced Slug Killer costs £3.95 for 250g, they are sold on line at garden organic or harrodhorticultral.com, or you can buy them from the local B&Q. There are a few other organic non-toxic pellets on the market such as Grow Aid Slug Gone, this is made from concentrated sheep’s wool and it irritates the slugs when they try and cross over it. These slug pellets pose no risk to birds and other wildlife.
Even so, use them sparingly – only using about four to six around the base of plants. Start to think about alternatively control for slugs and snails, traps and barriers are good and I always swear by horticultural grit with its sharp sides to keep slugs off sweet peas and other vulnerable plants.
If you grow hostas try and look for the blue leaved varieties that tend to be much better at keeping slugs at bay. I find that if you grow red lettuces the slugs don’t seem to like them so try growing one red, one green, one red, one green etc. Another way to avoid slug damage is grow plants on ‘hard’ – which means don’t put out plants when they are soft and young, as they are real fodder for the slugs. It will also help young plants to grow strongly, avoiding pests and diseases. I find that every year, as my garden gets tidier, the slug and snail population becomes smaller!
Other pests to look out for are aphids; there are 500 species in this country and so consequently don’t be surprised to see some on your allotment. They come in many colours, black, yellow or pink and sometimes they are fluffy white. They suck sap from the foliage and stems of a plant and sometimes from the roots. They love sappy young foliage and so this is why spring and early summer the time when they mainly cause problems is. They also carry virus diseases when they move from one plant to another and this can cause plants to become distorted by curling up their leaves or growing in a peculiar fashion.
Aphids excrete honeydew which is a sticky substance that appears on leaves, and then this in turn becomes a sooty mould. So you can see how pests often carry and cause diseases to plants too!
One of the plants affected by aphids on your allotment is likely to be broad beans; this aphid (black bean aphid) tends to form really dense colonies on shoots and leaves. One of the ways to counteract this, besides encouraging natural predators, such as ladybirds, is to pinch the tops of the young beans out; these are the nice juicy succulent bits that the aphids want. I tend to either squish them by hand or use a hose and blast them off, but this needs to be done on a regular basis as they quickly build up again.
Although ladybirds are a great natural enemy, their colonies tend to take a long time to build up so it is often necessary to use other methods to get rid of the aphids. There are chemicals such as Bayer Sprayday Greenfly Killer, but I think it is possible to control aphids without chemicals. It is possible to mix up some Ecover washing up liquid and spray that onto the plants, add a bit of cooking oil and mix it with some water in a spray bottle, just a squirt of Ecover and a teaspoon of oil to help it stick to the plant will do.