10 March^ 1919. J Apple Culture in Victoria. 147 



them, considerable damage to the flowers of fruit trees. lu fact, the 

 crop yields from the late-blooming apples during recent years have 

 been regulated largely according to the severity of the thrips' visita- 

 tion. If the weather be dry and warm during October, when the apple 

 trees are in bloom, much damage is done, but comparatively low tem- 

 peratures, with frequent intermittent showers at this time, practically 

 control this pest. 



During the blooming period of the 1918 season, frost was responsible 

 for considerable damage to the early-flowering varieties. While the 

 late sorts were blooming, many showers fell, but as these were alter- 

 nately followed by relatively long periods of comparative warmth and 

 calm, almost complete destruction of the blooms by thrips ensued. The 

 attack was so viruleiit that the London Pippin and Rome Beauty crop is, 

 in proportion to the area under these varieties, probably one of the 

 lightest on record for the State. 



J^atural expansion of the petals, to gradually admit sunlight and air 

 to the sexual organs of the flowers, in order to secure their healthy 

 development and facilitate pollination, is a condition essential to suc- 

 cessful fruitsetting. The adult forms of the thrips, now so well known 

 to fruit-growers, are proficient fliers and very active. The greatest 

 damage is caused to the vital organs of the blooms before the time of 

 opening. The adult insects gain admission to the flowers by wriggling 

 through small openings between the petals some time before their 

 general expansion commences. On entering the immatured flowers, the 

 insects attack the embryonic forms of the stigmas and anthers by suck- 

 ing their juice, thereby causing these organs to shrivel up. The petals, 

 in consequence of their inner surface being attacked in like manner, 

 prematurely wither and turn brown. Being weakened in this manner, 

 and because of the presence of a slight sticky secretion consequent on 

 the flowers having been made the habitation of the insects, the petals 

 are rendered incapable of expanding. When this condition is reached, 

 rapid reproduction takes place, and large numbers of thrips in the 

 different stages of their existence may be found inside the flowers. 



Luckily the first two or three weeks in October are usually suffi- 

 ciently cool and wet to control the thrips and afford the early-blooming 

 varieties, which include the vast majority of those under cultivation, 

 favorable conditions for setting. 



The thrips being very active and sensitive to agitation, quickly 

 evacuate their positions around the bloom buds on being disturbed by 

 rain, which destroys many of the early-matured insects, and prevents 

 others ascending to higher positions on the trees. When these gain 

 admission to the closed flowers, however, the case is different, as then 

 no amount of agitation will dislodge them. In dealing with thrips, it 

 is realized that, because of the great numbers in which they appear, 

 and the rapidity with which they multiply, the sprays used against 

 them should be destructive and act as a deterrent as well. Tobacco 

 water, benzol emulsion, coal-tar water, &c., have given fairly good 

 results on limited areas, but to satisfactorily cope with this pest in 

 large commercial orchards is a difficult proposition. 



