These little creatures, almost invisible to the naked eye, are undoubtedly the greatest menace to the grower. They are often unseen and unsuspected until their numbers are high and they can multiply at a devastating rate. If they find favourable conditions in the greenhouse or indoor growroom they can literally destroy a crop.
The first signs of their presence are small dead spots that appear in clusters on the affected leaves. This is followed by a general bronzing of the foliage and as the infestation increases, there will be visible deposits of fine webbing on the underside of leaves. Old fashioned methods of chemical control have never been successful for long as these creatures are very adept at developing resistance to each poison in turn. Man has responded by using ever more toxic chemicals to control them with an ever decreasing success rate. The side effects of this are the collateral destruction of hundreds of beneficial or neutral insects that would normally co-exist with the mites in some sort of balance.
The solution that biological pest control offers is the introduction of another mite called Phytoseiulus Persimilis which lives exclusively on two-spotted mites. If the population of pests is at a high level, the predator will multiply in relation to its food supply. Once the pest is reduced then the predator will begin to die out as well. A balance should then be achieved which will maintain the pest population at low levels, below the point at which they will cause visible damage. If the pests do begin to multiply beyond the predators’ capacity to consume them, the grower can then make small adjustments to the environmental conditions (temperature and humidity) that will favour the predators over the pests. Predator mites are known commercially as SPIDEX and can be purchased at Esoteric Hydroponics.
No comments:
Post a Comment