2(3 MISC. PUBLICATION 273, U. S. DEPT. OF AGRICULTURE 



seedlings, and in hot weather a weaker emulsion should be used to 

 prevent injury to the roots. While this treatment has given satis- 

 factory results in the experiments so far conducted, it should not be 

 adopted on a large scale until it has been demonstrated that it is 

 applicable on the particular type of soil at the nursery, and puddling 

 of the soil should be carefully avoided. 



Treating some soils, especially light sandy loams, with arsenical 

 compounds has been shown to be destructive to seedlings, and in many 

 cases it has left the ground in a toxic condition for 3 or 4 years. 



ROOT WEEVILS 



In forest nurseries of the Pacific Northwest the strawberry root 

 weevil has proved to be one of the most serious insect pests. Three 

 species are involved in this damage — Brachyrhinus ovatus L., B. 

 Tugosostriatus Goeze, and B. sulcatum F. 



The adults are small, browm, hard-shelled, wingless beetles about 

 one-fourth inch in length, with head extended into a snout. Wlien 

 the adult weevils emerge in the early summer they migrate on foot, 

 crawling everywhere, in search of suitable places for egg laying. 

 Eggs are laid only at the root crown of plants, and the small, white, 

 curled grubs develop in the soil, where they feed on the roots of 

 various plants. The life cycle is completed in 1 year, and the full- 

 grown larvae pupate in the soil and emerge as new adults the follow- 

 ing summer. 



Seedbeds can be protected from infestation by encircling them dur- 

 ing the migration and egg-laying period with barriers, such as boards 

 or metal strips placed on edge in the ground and painted with sticky- 

 substances, such as coal tar or sticky tree-banding material. Poi- 

 soned baits have also proved effective in destroying the weevils in 

 larger fields. An effective poisoned bait consists of 5 pounds of pow- 

 dered calcium arsenate and 95 pounds of ground dried-apple waste, 

 applied at the rate of from 50 to 70 pounds per acre. 



The most satisfactory method of control is through clean cultiva- 

 tion and rotation of seed and transplant beds, allowing infested plots 

 to remain fallow and be cleanly cultivated in alternate years. 



WIREWORMS 



Under certain conditions wireworms (Elateridae) {S3) may prove 

 to be troublesome nursery pests. They are most frequently found in 

 heavy, moist soil, where they feed on undecayed plant material and 

 small roots. These long, slim, cylindrical, hard-shelled "worms" with 

 feebly developed legs are the larvae of click beetles, which are most 

 easily recognized by the layman by their ability to flip into the air for 

 several inches when turned on their backs. 



No satisfactory method of controlling wireworms has been de- 

 veloped, and soils which are abundantly infested with them should be 

 avoided for nursery purposes. 



CUTWORMS 



From time to time cutworms make their appearance in forest 

 nurseries and do considerable damage to the young^ trees by feeding 

 on the roots or clipping off seedlings at the ground line. 



