Controling greenhouse pests

How to control greenhouse pests

A greenhouse may be the perfect place to protect your plants from the ravages of the winter weather, however it is also a wonderful refuge for pests and diseases. Humidity may be high and ventilation minimal during cold weather. Conditions may seem quite chill, however they are considerably warmer than outside and sufficient for insect pests and fungal spores to be active. The same is true in conservatories, where warmth from the house is often supplemented with background heating. The secret is to be vigilant and take quick action if problems arise.

Maintain air circulation

Space is often at a premium in a greenhouse; this only adds to the problem. If plants are crowded air circulation is even worse and fungal pests are a particular problem. Often half-hardy subjects such as fuchsias and geraniums have too much foliage which really starts to deteriorate by midwinter. If this is the case, cut the plants back by half and remove as much foliage as possible, especially all fallen and diseased leaves. Clean up around the plants, space them as far apart as possible after cleaning down the benches with Vitax Greenhouse disinfectant.  Containing citrus oils this concentrated cleaner is pleasant to use and it can be used on all surfaces in the greenhouse: staging, glass, pots and tools. Even though it is winter do ventilate your greenhouse as often as possible on mild days.

Scale insects and sooty mould

Insect pests thrive in the closed environment of a greenhouse or conservatory whether the atmosphere is damp or dry. Evergreens, especially citrus, are prone to scale insects. These lie hidden along the midrib on the underside of leaves, their presence usually given away by the presence of sooty mould on the upper surfaces. This black filmy deposit is caused by fungi populating the sticky secretions of the scale insects. Both the sooty mound and the scale insects can be difficult to eradicate. On small plants, carefully wiping the leaves on both surfaces can be successful.

The easy way to spray

In a greenhouse using Vitax Greenhouse Fumigator is an easy and effective way to kill off insect which are well hidden about the plants. All you need to do is make sure the greenhouse is as airtight as possible, then light the touch-paper and retire. The smoke (contains permethrin) kills flying and crawling insects and gets into all those nooks and crannies that a spray just would not reach.

Although Vitax Greenhouse Fumigator leaves no odour, you may not want to use it in a conservatory. In this situation Vitax Py Bug Killer Spray RTU is always worth keeping at hand. A contact insecticide (contains Cypermethrin) it is important to spray the upper and lower surfaces of the leaves and make sure the spray reaches those places that bugs can lurk. Vitax Py Bug Killer is only recommended for certain pests it is extremely effective and may give control of trickier problems like scale and mealy bug.

Mealy bug, which appears as raised greyish white felty bumps on leaves, flowers and stems has become a more familiar problem with the increase in the number of orchid plants in our homes. The waxy, felted coating of the pest makes it difficult to kill. Keep an eye open and be patient: Removing the individual pests with a cotton bud is one of the most effective ways of removing them. Some traditional gardeners recommend dipping this in methylated spirits before tackling the insects.

Just remember to get in there early – as soon as you spot and problem – and keep those traditional remedies to hand.

Andy McIndoe for Vitax