Arizona republican., 1916-04-09
THR|PS BLIGHT
 VALLEY ROSES
State Entomologist A. w. Merrill Tells How Pest Can Be Eradicated; Part of Move to Make Valley Big Rose Garden

Reports arc being received of the blighting of roses in the Salt River Valley according to State Entomologist A. w. Morrill,. This blight should not be confused with the common mildew which attacks rose leaves and buds and which is usually easy to control by spraying either with potassium sulfid, one-half ounce in a gallon of water, or with atomic sulfur'' at the rate of one ounce in gallon of water. The blight affects only the rose buds. not the leaves. and prevents the develop ment of perfect flowers. The trouble is caused by very small insect known as the grain thrips or flower thrips. Speaking of this insect and it's control, the state entomologist made the fol- lowing statement:
 This is an orange yellow insect which is about a twenty-fifth of an inch long in the adult stage. The nNmph or immature form is pale vel low in color. In form the insect is slender and sometimes described as worm like The young nymph is SC small that it can find it's way beneath the petals of a very small rosebud even before there is any opening vis- ible to the naked eye. The damage is most severe in varieties like the Amer ican Beauty in which the bud devel- Cpment is slow.
 There is no way of controlling these insects on rose bushes by spraying or by any application to the plants. In at least some cases however perfect rose blossoms can be produced by per- sistently picking off each blighted bud as soon as it. is evident that it is af- fecteG. When the infested buds are al lowed to remain upon the plants the eggs of the thrips. which are evidently laid al the bases of the petals. hatch and the young insects reach maturity after which they scatter to the new buds as fast as they appear increasing in numbers many times faster than the buds. By removing the buds as here advised and destroying them by burning. thousands of the young insects may be destroyed before they reach the adult or winged stage. have sue ceeded by the method described in growing perfect roses on bushes where previously all the buds were regularly olighted as fast as they appeared and at time when no other perfect roses could be found in the neighborhood The rose grower should examine the flowers Of all plants in the garden and such as prove to be particularly attrac- tive to the thr:ps should be given speriaI- Whether subject to noticeable injury or not. every kind of ! flower whicl, is attacked: bv the pest in large numbers should be picked regu- larly if possible and every blossom de- strOyed hy burning soon after it passes it's prime. These insects are very fond of sweet pea blossoms and by plarting sweet peas near roses and picking the flowers of the former regularly and burning them after they have done service as cut flowers a good many of ! the t.lrips which would otherwise con- 1 fine their attention to the rose buds may be attracted away and virtually 1 trapped. Fortunately. while the sweet peas are very attractive to the thrips no noticeable injury is done to them.
 "Thrips blight is quite similar to 1 frost injury in it's effects Rose buds of certain varieties, American Beauty and Crimson Rambler for instance af- fected by either the thrips or by frost
 will frequently develop in a normal or nearly normal manner if the outer dis cOlored petals are removed This should be done when the buds are about half grown or little larger. Varieties of
 roses with more fragile blooms than the ones named cannot. as rule be suc-
 cessfully treated in this way since the blossoms fall to pieces readily when the outer petals are removed