Orchard No. 21 Saline, Washtenaw County, 22 April 1926. 52 larvae on 10 trees. Sprayed but carelessly. Orchard No. 23 Chelsea, Washtenaw County, 21 April 1926. 4 larvae on 10 trees. Well cared for and well sprayed. Orchard No. 24 Jackson, Jackson County, 20 April 1926. 2 larvae on 10 trees. Well sprayed; old trees. Orchard No. 25 Jackson, Jackson County, 20 April 1926. 3 larvae on 10 trees. Well sprayed. Orchard No. 26 Jackson, Jackson County, 20 April 1926. 8 larvae on 10 trees. Well sprayed. Orchard No. 27 Chelsea, Washtenaw County, 21 April 1926. 10 larvae on 10.trees. Sprays every year; trees large; 90 years old. Orchard No. 29 Grass Lake, Washtenaw County, 21 April 1926. 4 larvae on 10 trees. Fair spraying. Orchard No. 30 Ann Arbor, Washtenaw County, 23 April 1926. No larvae on 10 trees. Orchard well sprayed and cared for; no dormant spray needed for 7 years. Orchard No. 31 Adrian, Lenawee County, 23 April 1926. 52 larvae on 10 trees. No spray for second generation used last year. Orchard No. 32 Adrian, Lenawee County, 23 April 1926. 6 larvae on 10 trees. Very well sprayed. Orchard No. 33 Jackson, Jackson County, 21 April 1926. 3 larvae on 15 trees. Very well sprayed. A review of the evidence presented, seems to show that many larvae succeed in surviving under loose bark-flakes in spite of the attacks of birds. Well sprayed orchards seem to harbor a minimum of such larvae but some orchards that to all appearances, have received good care, still serve as homes for a large number of larvae which actually escape destruction by birds during the winter, and still appear vigorous up to a time when the prospect for rearing large families of young are most promising. It would appear that the removal, by scraping, of all loose bark-flakes and the application of bands of burlap would prove very much worth while. June-beetles (Lachnosterna) June-beetles are the adults of white-grubs which are commonly found feeding on the roots of grasses. While the latter are always common enough, it is only at long intervals that the adult, winged beetles appear in Michigan in swarms capable of defoliating the trees on which they feed. Some of the states south of us suffer from such attacks more frequently. In mid-June, 1926, swarms of the adult beetles appeared in parts of Kalamazoo county where oaks, walnuts, elms, poplars and sometimes maples were attacked more or less seriously, the oaks suffering by far the most. June-beetles deposit eggs, preferably in grass sod, under the surface of the soil. In most cases the white-grubs from these eggs. require three years for development. All grass sod in the neighborhood of a district where such swarms of beetles occur, is pretty sure to develop white grubs in serious numbers the year after the attack of the beetles, and consequently such land should not be planted to root crops or left in grass sod at that time. In the vicinity of golf-links the case becomes complicated, since to leave the land in grass means to supply the creatures with an ideal food supply. It is imperative therefore that the beetles themselves be killed before the eggs are laid and this is most easily done by spraying the trees in the vicinity, and especially the oaks, with arsenate of lead in the customary way, otherwise these beetles wil! lay eggs in the sod and during the year following, the roots will be eaten off, resulting in the death of part of the grass. Root Maggots The spring of 1926 opened cool and moist. The soil warmed slowly and plants developed somewhat in advance of soil inhabiting insects. In consequence, the bean-maggot found itself still in the soil and only partially grown at the time when beans began to sprout. Furthermore, too large a proportion of the field beans were planted deeply, both of these factors. favoring the maggot. In following a row of beans where the drill or seeder had dipped in deeply-for instance where one wheel had traveled in a dead furrow, one could readily see that the deeply planted seeds had produced plants which required more time to germinate and to push their way up out Fig. 9.-Very young Bean plants attacked by Bean Maggots. of the soil, thereby giving the maggots, already in the soil, a better chance to establish themselves between the opening cotyledons and to destroy the bud. Many fields of beans, however, which seemed to be beyond hope turned out to be in better condition than at first appeared, although quite a few had to be reseeded. Fig. 10.-Work of Bean Maggot in sprouting beans, taken from infested field, much enlarged. Other factors favoring the maggot in normal years are late fitting of the field and the application of fresh manure. The bean maggot also made itself felt in cornfields, although Michigan corn never suffers from this pest as does corn grown further south. Both the cabbage-maggot, Phorbia brassicae, and the onion-maggot, P. cepetorum, were plentiful, the spring of 1926 seeming to favor the development of all root-maggots. The use of mercuric chloride solution, used in Fig. 11.-Adult flies of Cabbage Maggot, greatly enlarged. the proportion of one ounce to eight gallons of water was recommended for the two latter pests, and while the results were satisfactory, they fell short of being all that was desired. In using this solution the soil about the roots is wetted three or four times at intervals while the plants are still small. The Bladder Maple-Gall (Phyllocoptes quadripes) The small, hollow galls which are sometimes scattered over the leaves of soft maple have been especially plentiful in recent years. Very many samples have been sent in from various parts of the state. So numerous have they been and so thickly have they been crowded on the upper surfaces of the leaves that at times the leaves have been stunted and deformed, not reaching more than one-third or one-half normal size. The tiny mites which cause the growths are so small as to usually escape observation. It is said that a spray of strong lime and sulphur applied just before growth starts in the spring will control the majority of the mites and prevent the development of galls. |