Orchid Pests

When it comes to an orchid pest, some growers attribute the frequent appearance of dry or blackened flower sheaths, and the consequent loss of blooms, to a virus but there is no conclusive proof of this.

The consensus of opinion is that the condition is a result of a lack of air, or sudden chilling while damp.

The dry sheath may be removed by slitting both side 'seams' and pulling each half toward the leaf with a quick jerk.

This procedure may save the buds from orchid pests. Infrequently it will be found that buds have succumbed to wet rot inside an apparently healthy sheath.

It is likely that this condition results from steaming caused by the 'sweating' of an excessively heavy sheath that has been subjected to too much heat. Many growers make a practice of cutting off the tops of such very heavy sheaths as soon as the buds show at the base.

Cattleya Mossiae has a habit of forming the sheath months before the bud appears. This sheath very frequently dries up and turns black, but the buds usually survive.

In brief the rules for control of orchid pests and diseases are:

(1) absolute cleanliness;

(2) plenty of air and bench space, with no crowding of plants;

(3) immediate isolation of infected or suspected plants;

(4) proper control of humidity with no chilling while the house is wet;

(5) a routine system of spray with a noninjurious insecticide, perhaps alternated with fumigation by burning nico-fume;

(6) removal of armoured scale by brush or fine mist spray under pressure; and

(7) sponging fungus-infected spots with corrosive sublimate or copper sprays and dusting injured parts with sulphur to check the spread of rot.

When it comes to an orchid pest, the grower who keeps her plants in good health, providing the most favorable environment for vigorous growth and repotting at the proper time with fresh potting material, will cut to a minimum his troubles with pests and diseases. Plants with healthy bulbs, leaves, and roots are remarkably pest- and disease-resistant.

We again emphasize the necessity of handling all insecticides with extreme care. Exact attention should be paid to the precautions advised by the manufacturers, such as wearing a mask and rubber gloves when using the insecticide. The definite toxic effect of many of the new discoveries is still a mystery.

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