Monday, September 14, 2009

Biological control of plant pests

Biological Control measures at FitzGerald Nurseries

At FitzGerald Nurseries we have a strong commitment to achieve pest control through biological methods. Strict hygiene and close observation of crops is necessary to prevent pests establishing in the first place. Staff are being trained to identify pests, biological predators and they are familiar with Integrated Pest Management methods.

The following are pests successfully controlled at our nursery using Biological controls:

Vine Weevil (Otiorhynchus sulcatus):
We treat all our crops with a nematode (Steinerema) in April when general temperatures are above ten degrees centigrade and again in September by drenching with Nemasys L. The timing is very important to catch the Weevil larvae before they pupate. These treatments have given us practically 100% control on all our crops whether indoors or outdoors. It also means that we don’t use harmful chemicals in our composts or as sprays and have no subsequent handling problems with staff and customers.

Scarid Fly( Bradysia):
Up until 2007 scarid fly were causing problems in our young plant propagation areas. We introduced Nemasys F, a nematode formulation that achieves very good control and changed our cultural and watering practices. Nematodes are applied as a drench through the irrigation lines every two weeks all year round. This has the effect of never giving the Scarid a chance to build up their population to any great level. It also helps to control Thrips that occasionally occur. We find that it is cost effective (especially when done using the irrigation lines) compared to hazardous chemicals that did not always work well. There are no problems with re-entry periods for staff working and no effect on other biological controls we have in the plant propagation areas.

Spider Mites (Tetanychus):
In previous years two spotted Red Spider Mite have been a serious problem to contain and was a major problem to control with chemicals. Last year as a test we introduced predator mites (Phytoseiulus persimilis and Amblyseius californicus) in a contained area that was infected with Red spider mites on Clematis. We found that it not only contained the infection but eradicated it within one month and kept the plants ‘clean’ for the rest of the year. The mites were introduced at a rate of 10 per M2 every two weeks until control was achieved and then they were introduced at 5 mites per M2 after that until September.
After that initial success we then decided to go nursery wide and treated all covered growing areas since last April at a low rate(5 mites per M2) until the end of May and then at a higher rate in the months of July and August(10 mites per M2). During the one hot spell in June we used the Amblyseius as they cope better with warmer extremes in temperature than Phytoseiulus. We will again lower the introduction rate for September as the chances of infection reduces again. So far there are massive improvements in the health of our crops this year and we believe that next year there will be even less Red Spider Mite because we have broken the potential of eggs being laid over winter. Apart from the joy of not having to use chemicals, there where no upsets to deliveries or staff by having to apply chemicals.

Thrips (Frankliniella occidentalis):
We have occasional break outs of Thrips mainly on plants brought in to the nursery. We find that the application of Nemasys F reduces their numbers but we also introduced this year Amblyseius cucumeris to our arsenal of predatory mites. They quickly brought a problem area back under control and have kept it virtually free of Thrips since then. They also have the ability to survive on flower pollen etc, when there are no other forms of food for them available so they are always ready should another Thrip come along.

Apart from the introduced predators we have noticed that other naturally occurring predators have made their presence felt since we have hung the sprayers up. Mainly Aphid are being much reduced by a parasitic wasp and some lacewing are noticeable too. Spray deposits are not a problem any more on our shiny leaved plants and so the crops look healthier as well.
This we hope is just the beginning of our long term plan to eliminate insecticides and fungicides from our production but already we are glad to report our main aim to eliminate insecticides is becoming a reality. We are working on a range of activities including use of recycled composted waste for our potting substrate, water recycling and rain harvesting. It is satisfying to be making progress on this ongoing commitment to sound modern environmentally friendly practices.
MyPlant Team.


  1. Thanks for sharing the Biological Control measures at FitzGerald Nurseries. It was nice going through it. keep it up the good work.

  2. Hello. Please could tell me where you get your predator mites from for the control of spider mite? The places that are in England do not post to Ireland.


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