Table 2 — Level of damage by gouty pitch midge on the new 

 shoots of ponderosa pine 



In fo^ti/M^ 



II 1 lliifl 1 



class 



Number of tips damaged 

 Mean Range 



(progeny) 















Percent 

 46 



1 



2.5 



< 5 



20 



2 



18 



6-32 



23 



3 



49 



33-67 



10 



4 



84 



68-100 



2 



Table 3 — Analysis of variance and variance components of 

 transformed data 



Source of 

 variance 



df 



MS 



Variance 

 component 



Block 



4 



0.367 



0.0005 



Stand 



47 



.089 



.0009 



Family in stand 



182 



.300 



.0012 



Experimental error 



916 



.012 



.0017 



Within plot 



2,608 



.007 



.0070 



DISCUSSION 



Individuals and families of ponderosa pine vary in their 

 response to infestation by the gouty pitch midge. The high 

 individual and family heritabilities could result in fairly 

 good genetic gains in resistance. The estimated gain that 

 could be realized for one unit of i was 10 percent for family 

 selection, 8 percent for individual selection. 



Gouty pitch midge can be devastating to ponderosa pine. 

 At the Lone Mountain tree improvement site the epidemic 

 started in the mid-1980's. In 1986 many trees were dead, 

 and on many others nearly all shoots were dead or dying. 

 It will take a long time for this progeny test to recover. 



Epidemics caused by the gouty pitch midge are rare in 

 wildland forests. The biggest impact has been in test 

 plantations, namely in a monoculture complicated by close 

 spacing and foreign germ plasm. Nonetheless, a natural 

 level of resistance should be maintained. It is probably not 

 necessary to increase the level of resistance in the wildland 

 population, unless the midge becomes a serious pest in 

 forest plantings. The tree breeder should consider resis- 

 tance in the selection scheme to make sure adequate 

 resistance is maintained. This can be assured by carefully 

 correlating shoot character and resistance to the midge. 



REFERENCES 



Austin, L.; Yuill, J. S.; Brecheen, K. G. 1945. Use of shoot 

 characters in selecting ponderosa pines resistant to resin 

 midge. Ecology. 26: 288-296. 



Duffield, J. W. 1985. Inheritance of shoot coatings and 

 their relation to resin midge attack on ponderosa pine. 

 Forest Science. 31: 427-429. 



Eaton, C. B.; Yuill, J. S. 1960. Gouty pitch midge. For. Pest 

 Leafl. 46. Washington, DC: U.S. Department of Agricul- 

 ture, Forest Service. 8 p. 



Namkoong, G. 1979. Introduction to quantitative genetics 

 in forestry. Tech. Bull. 1588. Washington, DC: U.S. De- 

 partment of Agriculture, Forest Service. 



SAS Institute. 1979. SAS user's guide: statistics. Gary, NC: 

 SAS Institute. 494 p. 



Steel, R. G. D.; Torrie, J. H. 1960. Principles and proce- 

 dures of statistics. New York: McGraw-Hill. 481 p. 



U.S. GOVERNMENT PRINTING OFFICE: 1988—573-039/61,049 REGION NO. 8 



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