The aphids attack the opening buds, the young fruits, the growing shoots, and the leaves, sucking the plant juices from the succulent parts by means of long, very slender, tube-like beaks, which they thrust through the skins of the affected organs into the soft tissues beneath. They weaken the blossom buds by removing the sap; they dwarf and deform the apples so that varieties of ordinary size frequently fail to grow larger than small crab apples, and the fruits have a puckered appearance about the calyx end; they suck the juice from the growing shoots, dwarfing them; and they cause the leaves to curl, and if the insects are present in large numbers, to dry up and fall off. They are more injurious to the growth of young trees than of old trees. In old trees their chief injuries are on the fruit.
This species of aphids are easily killed in the adult stage by certain contact sprays. Winter applications of lime sulphur cannot be depended on to destroy eggs. Poison sprays such as arsenate of lead are not eaten by this type of insect, and consequently are ineffective remedies for aphids. Kerosene emulsion is effective but is uncertain in its effect on the foliage of the trees. The best available sprays are the tobacco decoctions, of which the one most widely in use is "Black Leaf 40," a proprietary tobacco extract, made by the Kentucky Tobacco Products Company, Louisville, Kentucky. This material is used at the rate of one gallon in one thousand gallons of spray. It may be combined with lime sulphur, lime sulphur arsenate of lead, Bordeaux, or Bordeaux arsenate of lead, not with arsenate of lead alone.
The ideal time to spray for these aphids is just as soon as all or nearly all the eggs appear to have hatched. Observations made in the University orchards this season indicate that all the eggs hatched before the blossom buds began to separate. After the leaves expand somewhat and the blossom buds separate, the aphids are provided with more hiding places and are more difficult to hit with the spray. Unfortunately, spraying at this time would require an extra application in addition to the cluster bud (first summer) spray (made for scab, curculio, bud moth, spring canker worms, etc.), and would thus add seriously to the cost of the season's operations. Spraying for aphids at the time of the cluster bud spray is, however, highly effective, and in general it is advised that this method be followed. If, however, previous experience has shown serious losses from aphids, or if they are present in extremely large numbers, the extra application may be well worth while.—Ill. Agri. Exp. Station.
Annual Report, 1915, Duluth Trial Station.
C. E. ROWE, SUPT., DULUTH.
A rosa rugosa hybrid rose grown by C. E. Rowe, Duluth.
Although this was an off year for apples, results were probably as good here as in other sections of the state. The spring gave promise of an unusual crop, but the constant dropping of fruit during the summer months left us with about two-thirds as many apples as were harvested in 1914. The quality was much poorer, owing to extremely cool weather and the presence of scab in many localities.