INTEGRATED PEST MANAGEMENT (IPM) FOR ROSES

Integrated Pest Management means the prevention and control of pests and diseases, using all existing crop protection techniques and experiences. Measures to prevent pests and diseases are the main objects of integrated pest control. Hygiene as well as growing practices play an important part in this method Other vital ingredients of I.P.M. are; supervision, biological control, mechanical and chemical control. The latter is mainly used as a corrective measure either before or during the growing season.

Biological Control

This is the control of pests and diseases by introducing natural enemies and or spraying bio-insecticides

These controls can be classified into three groups:

(1) Predators: - predatory mites, midges, bugs and beetles

(2) Parasites: - parasitic wasps and flies.

(3) Micro-organisms: - nematodes, fungi, viruses, and bacteria.

The following pests can be successfully controlled by IPM methods

Red Spider Mites (Tetranyanychus urticae):

Introductions of predator Phytoseiulus persimilis will control outbreaks for regions having temperatures up to 30^oC. For regions with temperatures above 30^oC; Amblyseius californicus should be used. Mixtures in some cases can be applied when the both temperature regimes occur. Always apply at the beginning of the infestation period.

Whitefly (Trialeurodes vaporarium and Bemesia tabaci)

Whitefly can be controlled by releasing the parasitic wasp Encarsia formosa or Macrolophus caliginosus. The latter is used in higher temperature regimes and where chemicals are used regularly. Applications should start right at the beginning of the first sightings.

More introductions are necessary in the temperate climate than in the tropical and sub-tropical climates.

Thrips (Onion thrip -thrip tabaci, Western Flower thrip - Frankliniella occidentalis)

There is a wide range of predators and micro-organism that can be used:- Amblyseius degenerans, Orius insidiosis and Orius laevigatus, each with its own strong points which can be applied to special regions and crops under glass, plastic and shade netting. Timely introduction are necessary in order to obtain economical results for the grower plantation owners.

Aphids (Aphis gossypii, Myzus persicae, Macrosiphum euphorbia, Aulacorthum solani)

The introduction of Aphidius colemani, Aphelinus abdominalis, Aphidoletes aphidimyza, Hippodamia convergens will give good control of the various aphid infestations, which of course can be devastating since they produce live bearing offspring. Timing is essential. While one parasite is good in finding spot infestations others are good for bigger infestations and are used for blanket applications to cover the whole crop at one time.

Micro-organisms

Fungi are now well established as approved insecticides, the only drawback being that they can only be used in regions where the relative humidity is high. 80 - 95% is well suited to these groups of insecticides. In the rose growing industry the following products can be used.

(1) Mycotal W.P: Consisting of Verticillium lecanii for control of whitefly and thrips.

(2) Vertalec W.P. Consisting of Verticillium lecanii for control of aphids.

Verticillium lecanii is a commonly found fungus. It contains the spores of the fungus strain lecanii and is very effective against whitefly and thrips, while another strain of the same lecanii is effective against aphids. Verticillium lecanii is wide spread in temperate and tropical climates.

Nematodes

Three different parasitic nematodes are now commercially available.

(1) Steinernema feltiae for control of scarid flies

(2) Heterorhabditis megidis for control of black vine weevil

(3) Phasmarhabditis hermaphrodita for control of garden slugs (Arion hortensis), Common or gray field slug (Deroceras reticulatum), the large black slug (Arion ater) the Keeled slug (Milax bedapestensis) and the common garden slug in its early stage (Helix aspersa).

The nematodes are suspended in water and applied to the soil through irrigation equipment/knapsack sprayers or watering cans. The type of soil structure is very important as the dampness of the soils since this is what carries the nematodes through the substrates in search of a kill.

Bacteria

(1) Bacillus thuringiensis is a good example of a bacteria preparation, which is known worldwide. It is marketed as a caterpillar insecticide

From the above it can be seen that IPM can be achieved successfully on roses, but this is provided that chemical treatments are reduced to a minimum so that the natural enemies have a chance to survive and control individual pests, and also to stimulate local predators and parasites in each region. While the system of IPM changes in different regions the natural enemies stay the same. It has been proved for example that Red Spider Mite control in the tropics uses less predators than those in temperate climates. The number of natural enemies used depends on the regions climatic conditions and can vary enormously.

In the Netherlands cut flowers grown under IPM conditions are being marketed in special sleeves and are said to get a higher premium than those treated with chemicals.

When IPM flowers are exported they should be sprayed with a strong pesticide just before shipment so that all insects are killed before leaving. Usually the natural enemies have done their job so efficiently that no insects can be found on the flowers anyway.