Home > Pestech Australia suggest the use of natural pyrethrum means insecticides and beneficials can co-exist in an IPM program

Pestech Australia suggest the use of natural pyrethrum means insecticides and beneficials can co-exist in an IPM program

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Natural pyrethrum is often overlooked as an insecticide in an IPM program, perhaps because it has not been strongly promoted or economically viable until recently.

Discussions on the use of ‘softer’ insecticides in conjunction with beneficials in an effort to control pests in an IPM program are common among growers.

The food production future will include biocontrol agents other than beneficial parasites, predators and plant breeding. Viral and bactericidal agents are already in use and fungal agents are gaining acceptability. This push is to control insect and mite pests without exposing greenhouse workers to pesticide dangers during and following application, and to ensure our blemish-free produce is eaten without pesticide residues. 

Many major growers have done their sums and have decided not to entirely go the beneficials or biocontrol agents way, relying on the application of natural pyrethrum only when pest insect population levels threaten loss of plant vigour and before damage occurs. This requires routine inspection for pest development, particularly being aware of new ready-to-mate adults.

The use of natural pyrethrum provides growers with an instant kill of almost 100% of a population, however if pest numbers begin to rebuild another spray can be carried out. Weekly or fortnightly applications is not recommended however, spraying only when crop value is at risk will save money and effort.

Natural pyrethrum has no residue beyond a couple of hours, meaning workers can re-enter immediately after the spraying is completed, which is particularly important during harvest as crops sprayed in the late afternoon can be harvested, and eaten, the next day.

Furthermore, with the use of natural pyrethrum it is impossible for spraying workers to build up to chronic poisoning levels due to it being so rapidly metabolised and eliminated by mammals.

Natural Pyrethrum has been used on people and animals in agriculture, commerce and homes for over 100 years, with thousands of scientific papers being written on both efficacy and toxicity issues.

Despite these benefits however, the question still remains for some as to what circumstances one would consider using natural pyrethrum in a protected crop environment, and whether it fits into an IPM program.

Yes it does. IPM involves choosing the variety/cultivar for its propensity to deliver the most saleable product at the highest yield (preferably with an inbuilt resistance to fungal, viral and pest attack), add whatever it takes to deliver optimum plant nutrition. And then there’s the physical microcosm of the plant environment.

Having set in place the plant choice, nutrition and environment legs of IPM, pests always appear and they need to be managed.

Within two or three generations, the exponential numbers can easily halve the potential size of the plant, and what survives of the flowers and fruit is often marked and downgraded.

When and how to fit in pesticides and beneficials is another important factor. Waiting too long to introduce beneficials, for example until pests are well established, can be expensive and they still may not control the pests.

An option is to spray the plants with natural pyrethrum to immediately kill off the pests at an early stage of plant growth and, if desired, beneficials can be introduced in smaller numbers as soon as pests are seen. As there is no residue beyond a day, beneficials are on a more equal footing.

However, if in the critical weeks leading up to harvest the pest numbers are getting beyond the beneficials’ ability to control, to avoid marking or downgrading another natural pyrethrum spray can eliminate all the pests. The beneficials will also be lost, however as it is close to harvest the reintroduction of beneficials is not cost effective anyway.

If there are still some weeks to harvest and the pest population is concentrated in one section of a crop, the natural pyrethrum application can be confined to that area to clean out the pests and allow beneficials to resume their control as and when low pest numbers return to the treated area.

Finally, and particularly in sheltered environment crops, a spray of the remaining pest population in the remnants of a crop being removed at cleanout may be advisable to avoid spreading infestation during removal.

The 80g/L pyrethrins, 480g/L piperonyl butoxide formulation of PyBo Natural Pyrethrum Insecticidal Concentrate is 20 times stronger than most of the home garden products and 6 times stronger than the products some growers use. It is a solvent-free formulation, registered for use on all crops.

This advice on the use of natural pyrethrums in an IPM program was supplied by Pestech Australia .

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