RESULTS 



Initial results comparing numbers of ectomycorrhizal 

 short roots on shallow, as opposed to deep, lateral roots 

 indicated no significant differences between treatments. 

 Significantly more short roots occurred on the shallow 

 laterals than on the deep. We therefore discontinued use 

 of deep lateral roots in the evaluation process and pres- 

 ent only results using surface lateral roots. 



Differences between treatments were small, usually 

 sporadic, and nearly balanced— there were almost as 

 many cases where ectomycorrhizal short roots were more 

 numerous on treated seedlings than on untreated seed- 

 hngs as there were cases where they were fewer (tables 

 2, 3, 4). Across the various nurseries no consistent 

 patterns of effects emerged between specific herbicides, 

 species, or treatments. Considering all nurseries, cases of 



significant interactions within a nursery occurred 

 between all three variables at one location or another 

 (table 5). 



Although differences were small, the most consistent 

 related changes were slight reductions in numbers of 

 ectomycorrhizal short roots on Douglas-fir seedlings 

 treated with all three herbicides at the Montana State 

 Nursery, Douglas-fir seedlings treated with Bifenox at 

 the Forest Service nursery at Coeur d'Alene, and slight 

 increases in ectomycorrhizal short roots on lodgepole 

 pine seedlings treated with Bifenox and DCPA at the 

 Forest Service, Lucky Peak nursery (tables 3, 4, 5). 

 Statistical comparisons based on differences in percent- 

 age of ectomycorrhizal short roots were almost identical 

 to those based on actual numbers as seen in tables 2, 3, 

 and 4. Therefore, these data have not been presented. 



Table 2.— Comparisons of herbicide treatmerits by mean numbers of ectomycorrhizal short roots (cm) on 10-cm segments of main lateral 

 seedling root, based on 30 samples for each treatment 



Nursery 



Coeur d'Alene Albuquerque 



Treatment 



Ponderosa pine 



Engelmann spruce 



Douglas-fir 



Grand fir 



Western larch 



Ponderosa pine 



X 







X 







X 







X 







X 







X 







Control (no herbicide) 



38.0 



9,0 



40.6 



12.6 



30.9 



7.4 



24.2 



11,3 



22.0 



4.5 



42.6 



14.6 



Bifenox 



























Bif. 1x1, PS2 + PG3 



37.3a'« 



9.8 



_5 





23.9a* *6 



5.8 



28.4a 



8.2 







38.1a 



13.7 



Bif. 1 X, PS 



46.8b* * 



11,6 







24.6a*- 



6.6 



26.5a 



7.5 







45.2a 



10.7 



Bif. 1 X, PG 



40,7a 



11,6 







26.6b** 



6.4 



29.3a 



9.9 







46.9b 



16.1 



Bif. 2x, PS 



42.9a 



11,4 







22.6a** 



4.9 



32.1a 



8.5 







43.5a 



8.8 



Bif. 2x, PG 



45.5b** 



9.6 







30.0b 



6.4 



27.7a 



7.1 







40.6a 



13.6 



DCPA 



























DCPA 1 x , PS + PG 







36.2a 



9.8 











23.6a 



12.8 



45.1a 



10.0 



DCPA 1 x, PS 







47.6b** 



8.9 











21.4a 



12.1 



44.6a 



15.1 



DCPA 1 X, PG 







37.4a 



11.0 











24.1a 



13.1 



47.1a 



8.9 



DCPA 2x, PS 







44.8b 



11,6 











18.5a 



5.3 



49.6b*' 



12.1 



DCPA 2x, PG 







41.9a 



8.4 











21.1a 



3.8 



41.8a 



13.8 



Napropamide 



























Nap, 1 x, PS + PG 



31.2a** 



8.9 



37.8a 



9.5 



25.0a** 



6.7 



27.2a 



9.9 







47.9a 



9.1 



Nap. 1 x , PS 



36.0a 



11.7 



38.8a 



15.4 



26.9a 



7.8 



25.1a 



7.6 







42.8a 



15.7 



Nap. 1 x, PG 



42.0b 



9.1 



36.3a 



12.9 



27.9a 



8.7 



26.6a 



14.1 







34,1b** 



11.1 



Nap. 2x, PS 



32.9a 



9.6 



32.3a** 



12.1 



27.9a 



7.3 



32.2a 



16.7 







38.6b 



15.1 



Nap. 2x, PG 



32,5a 



7.1 



34.1a 



9.8 



30.4b 



5.1 



27.0a 



8.9 







45.3a 



10.4 



M X = applied concentration according to manufacturer's recommendation, 2x = double concentration, for actual concentration of active ingredient (see 

 table 1). 



^PS = immediately postseeding. 



2PG = postgermination, usually 4 to 5 weeks after seedling emergence. 



""Treatments within a single fierbicide group and species (down column) ttiat do not stiare a common subscript letter are significantly different to at least 

 a = 0.05 level, Duncan's multiple range test. 

 ^Dash indicates ttiis combination not tested. 



^" = treatment differs from appropriate control (tiead of column) to at least a = 0.01 level, Duncan's multiple range test. 



3 



