Time to reap what you have sowed
Glasshouses are a great addition to a garden, allowing the keen grower to propagate nearly all year round, get a head start with seed sowing and enjoy tender plants out of season. They’re also attractive to insects who enjoy the snug indoor accommodation and plentiful supply of food.
While low levels of pests can be tolerated, what do you do when there’s an infestation and how can you prevent them?
Glasshouse/greenhouse hygiene is a good starting point. An annual clean in autumn or winter and disinfecting of benches and floors will disrupt the life cycles of many that choose to overwinter in your digs. Good ventilation will help with humidity levels, and try not to overcrowd the place with plants.
Check new arrivals for any insect baggage they are carrying with them – the undersides of leaves are often a hiding place.
Hanging yellow fly traps are a simple method of controlling and monitoring fly populations.
Weeds can be a host for a variety of unwanted visitors so keep on top of them.
If you make regular patrols you will spot problems before they get out of control and many of these creatures can simply be removed by hand.
However, sometimes it can feel as if you’re overrun by them so here’s a guide to some methods for the most common culprits.
When you brush past a plant in the greenhouse and a cloud of white flies comes out, then you have whitefly. A common glasshouse pest, it’s a sap sucker, and you’ll be able to detect it by sooty marks on your leaves – this is a mould growing on their sticky excreta.
Leaves turn yellow and eventually drop off with large infestations.
Insecticides, whether organic and or chemical, will need repeated applications.
Organic insecticides are made from
plant extracts so can be used on edible crops. But bear in mind that with any insecticide you run the risk of killing beneficial insects as well, so it can be counterproductive and upset the natural balance in your garden.
An alternative to sprays is using biological controls. This is where you release beneficial insects that will eat the undesirable flies.
In this case it’s a parasitic wasp called Encarsia which gobbles up the larval form of whiteflies. It’s important that you don’t use insecticide at the same time as that will kill the wasps as well.
As for the black mould, just wipe this off with a damp cloth.
The red spider mite is another sap-sucking insect which is having a ball in this dry, warm summer.
Usually found in warm glasshouses and conservatories, it can holiday outside in the garden when the ■ It’s harvest time for loads of crops so catch fruit and veg at its best, either for eating now or storing for the winter. Onions are ready when the foliage starts drooping over. You can tell if sweetcorn is ripe by squeezing a kernel, milky juice should come out.
■ Watering and feeding remains top priority, especially for any pots, troughs, hanging baskets and containers. ■ Finish pruning apple trees that are fan, cordon or espalier.
■ Look after pond life – keep water levels topped up, remove blanket weed and cut back yellow foliage on pond plants.
■ Dry weather is great for getting paint jobs done such as sheds, fences or furniture that weather’s right. It’s not fussy about which plant it lives on either, so ornamental as well as fruit and veg are all prey.
The mites are so small you’d need a need a face-lift. Is it time to try out a new colour scheme?
■ ■ Take a walk around the garden and see if there’s any seed ready for collection.
■ magnifying glass to see the culprits but the damage they cause is visible to the eye – a fine mottled yellow appearance on the leaves and sometimes they weave a fine web
Trim hedges.