NURSERY PRACTICE FOR PRAIRIE-PLAINS PLANTING 139 



mon in this group is the cottony maple scale. (3) The mealybugs, 

 which are oval in form and soft-bodied, usually appear as if they had 

 been dusted with flour. The European elm scale belongs to this 

 group, but during its third stage it lacks the dusty covering and has a 

 white, waxy fringe around the outer edge of the body. 



While scale insects are not likely to cause serious damage to seed- 

 lings during the short time in the nursery, the stock should be kept free 

 from scales lest the pests be transported to the field. The most com- 

 mon control measure is to spray with a dormant-strength miscible 

 oil, oil emulsion, or lime sulfur, preferably in the spring just before 

 the buds open. Such sprays are on the market under different pro- 

 prietary names and should be used according to the directions of the 

 manufacturers. With the heavy oils there is a possibility that dor- 

 mant strengths will injure some of the thin -barked seedlings. During 

 the growing season a summer white-oil emulsion or a summer strength 

 of lime sulfur may be used, but these usually are not so effective as 

 the dormant sprays. Usually none of these treatments will give com- 

 plete control in one season, and consequently if only a small portion 

 of the nursery stock is infested it should be destroyed and not sent to 

 the field. Under more serious conditions it is possible that fumiga- 

 tion might be used for some of these scale insects at the time of ship- 

 ment. 



Injurious Mammals and Birds 18 



Mammals and birds may cause considerable damage to some species 

 in the nursery by digging up or pilfering the seed shortly after it has 

 been sown or by nipping and breaking off the seedlings as they emerge 

 from the soil. Damage may also be done to larger seedlings by mam- 

 mals which feed on the bark, roots, and leaves of the trees. Mammals 

 usually cause more damage than birds in nurseries growing deciduous 

 stock. Protection must be extended to include the seed and seedling 

 stage in the nursery as well as in the heel-in ground. 



FIELD MICE 



Straw mulches used on seedbeds over the winter are especially at- 

 tractive to mice and other rodents, as are the weeds and grass along 

 fence rows. Population of rodents can be greatly reduced by burning 

 out and destroying this vegetation. Among the genera of mice which 

 make depredations on recently sown seed are various species of the 

 white-footed field mouse (Peromyscus), meadow mice (Alicrotus), and 

 the small, brown, pocket mice (Perognaihus). These do most of their 

 damage by digging up the seed in the rows shortly after it has been 

 sown. Very often more damage is done by exposing the seed in this 

 way or covering it too deeply than in the amount eaten. These mice 

 are most easily controlled by means of grain or other baits poisoned 

 with strychnine or other toxic agents, but the methods used for the 

 different species should be governed by the differences in their feeding 

 habits. 



1? The section on mammals and birds constitutes a revision and enlargement of a chapter on rodent control 

 prepared by Harold Haecker and F. E. Garlough, of the then Bureau of Biological Survey, in the manual 

 "Seed and Nursery Practice in the Shelterbelt Project" mimeographed by the Forest Service March 23. L936. 



