If you garden for long enough you will pretty end up at sometime dealing or seeing every pest and disease plant can get, this year we have had a massive whitefly problem. As much as this has turned into an infestation and all of our broccoli, cauliflower, cabbage and potatoes are covered in whitefly, it has been a opportunity to try out many techniques which the internet has recommend to see which ones will control whitefly.
How Can You Recognise Whitefly
Whiteflies are very small sap sucking insect related to the aphids, mealybug and scale insect family. These whiteflies are generally found on the underside of leaves and when the plant is disturbed fly away.
Whitefly adults look like small white moth and their body and wings are covered in a powdery white wax, their larvae or nymphs are flat oval shape and more look like an aphid. Whitefly can develop from a few whiteflies to masses in short time due to the that a complete life cycle can be just 18 days and the adult female can lay hundreds of eggs.
Why are Whitefly a Problem?
Whitefly in small numbers won’t cause any noticeable damage on plant, however if not controlled their numbers can turn from small to an infestation in a very short time. In large number they will affect the plants growth, cause discoloration of the leaves and nutrient deficiencies. Whitefly can transmit viruses and diseases from other plants to healthy plants.
How to Control Whitefly Effectively
Below is a list of ways we have found to control whitefly and if they were effective. We have completed this test and giving each option 2 weeks to work.
Blow them away with a leaf blower
A lot of people recommend that using leaf blower to disturb and blow the whitefly away. They say they don’t like to be disturbed and their soft body become damaged killing them. We found this method to not be effective at all.
Use your hose to wash them off
A lot of people recommend turning your hose onto jet and wash them off. Again, they said they don’t like to be disturbed and it would damage their soft bodies killing them. This is did not worSpk.
Spray them with horticultural oil
Spray your horticultural oil all over plant making sure the underside of the leaves is covered. This seems to have very minimal impact. The issue with horticultural oil is that you are dealing with both a flying insect, larvae and eggs. Horticultural oil is fine with controlling the eggs and larvae, however, does nothing to the flying female adults which can lays more eggs.
Spray them with a potassium soap spray
Spray potassium soap spray all over the plants making sure the underside of the leaves is covered. Again, this seem to have minimal impact due to it only being able to kill the larvae and eggs.
Spray with neem oil and potassium soap spray
By this stage in our garden, we have a lot of whiteflies attacking our plants and now our brassicas and potatoes are covered in whitefly, so I went out on all out approach. I used a mixture a neem oil and potassium soap and sprayed the plants. This kills the flying whitefly adults, the larvae and eggs. We applied this twice one week apart.
Even after the first spraying, I returned to the plants in the morning and there were only minimal whitefly hanging around. After the second spraying there was no evidence of any whitefly.
Spray with pyrethrum spray
We never used this as we don’t keep this or use it however, I believe if you combine the pyrethrum and potassium soap, or horticultural oil would also work well.
Attracting natural enemies
Whiteflies have natural enemies which are lacewings, ladybirds and hoverflies, however these insects can control whitefly when their numbers are few not thousand of whitefly. But by encouraging beneficial insect to live within your garden it can minimise the chances of ever getting whitefly.
Some of the plants we recommend in planting to encourage lacewings, ladybirds and hoverflies are cosmos, corn flowers, calendulas, marigolds, nasturtiums, salvia, and sweet alyssum.
Our Final Reflections
In our garden we hate using sprays of any sort to control pests because they can kill more insects than just the intended species, which was whitefly, this can throw your whole garden eco system out of balance. Another reason is that its costly in both time and money having to spray.
Prevention and early detection of pest is the best solution. The reason why we had whitefly this year is because we chose to grow broccoli over summer under shade cloth, it did exceptionally well and produce a heap of head and side shoots for us. It wasn’t until the end of summer when the whitefly hit us, however this summer when growing the broccoli, I will be covering the side with insect netting and plant more plants in the area to attract beneficial insects.