in some plantations (Curtis and Foiles 1962). Because of the virulence of some diseases, 

 the speed with which they act, and the investment made in establishment of regeneration, 

 it is important to maintain efficient forest disease surveys. 



Insects. --Young seedlings may be attacked aboveground by grasshoppers, cutworms, 

 aphids, and bark- chewing beetles. One instance of heavy feeding by tussock moth in a 

 ponderosa pine plantation has been recorded (Curtis and Foiles 1962) . Root-feeding 

 insects, such as grubs, weevils, wireworms, cutworms, root aphids, and root bark 

 beetles, do their greatest damage to tree seedlings. Ponderosa pine seedlings are 

 attacked by insects that reduce growth, deform, and occasionally kill trees. Insects 

 causing this kind of damage include tip moths or twig moths, weevils, and midges and 

 other gall-forming insects. Bark beetles, especially those of the genus Ips , can be 

 very destructive to small, thin-barked pines. Insect populations and the damage caused 

 by them vary greatly by years and locations. Efficient insect surveys will help to 

 indicate potentially hazardous insect populations so they can be avoided or controlled 

 if possible. 



Climate. — Injury and mortality from climatic elements account for only a small 

 percent of losses in established ponderosa pine regeneration. Extremes of climate or 

 weather can be very destructive, however, especially in plantations grown from the 

 wrong seed source. Snow and wind are also capable of causing understocking in sapling 

 stands . 



Mammals. — Mammals such as ground squirrels, pocket gophers, rabbits, hares, porcu- 

 pines, and deer can cause malformation or mortality of stems of apparently established 

 seedlings by their feeding. Defects often develop in the trees if they survive the 

 attacks. The feeding of these animals is usually confined to small areas, and reflects 

 either habitat conditions or sudden population increases. Nevertheless, understocking 

 to a greater or less extent can result. Hares (Hall 1971), porcupines (Baker and 

 others 1921; Wilson 1952), pocket gophers (Dingle 1956), and deer (Adams 1951a, b) are 

 probably the most common and the most destructive. 



The most common injury to established regeneration is from rodents. For control, 

 the particular mammals causing damage must be identified. Keys are helpful in dis- 

 tinguishing these animals and the damage they inflict on the tree (Pearce 1938, 1947; 

 Lawrence and others 1961) . 



Rabbits and hares are perhaps the easiest to control by the distribution of 

 poisoned grain or alfalfa in suitable places, although the proper timing may not be 

 evident until some feeding activity has been observed. Professional wildlife personnel 

 can be helpful as advisors. 



Various methods have been employed to reduce porcupine populations, but baiting 

 with wooden blocks containing strychnine is the simplest and most effective (Hooven 

 1971) . Trapping and poisoned baits have been used to control pocket gophers (Dingle 

 1956) and other rodents. Most poisons are potential hazards for other animals, and 

 should be used under the supervision of the Fish and Wildlife Service. 



Where deer populations become excessive, their browsing and trampling can be very 

 destructive. In northwestern Montana, effects of deer browsing on planted and natural 

 ponderosa pine seedlings were compared inside and outside of fenced deer exclosure 

 plots (Adams 1951a, b) . On the unfenced plots, over half of the planted pines were 

 killed or heavily browsed the first year; more than 80 percent of the trees were dead 

 after 4 years. Browsing also destroyed more than 80 percent of natural seedlings in 

 a similar test. Regulating deer numbers by hunting, or increasing the amount of other 

 browse available are possible methods of reducing deer damage. In plantations where 

 intensive treatment is possible, the coating of leaders with chemical repellents has 

 provided good protection from deer for 1 year in the Southwest (Heidmann 1963) . 



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