INSECT S. DISEASE 'MANAGEMENT

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1 spiclq PRONG FOREST 'Alpo INSECT S. DISEASE 'MANAGEMENT A3 USDA FOREST SERVICE NORTHERN REGION State & Private Forestry Missoula, MT November 1978 Report No NONEFFECTIVENESS OF RIBES ERADICTION AS A CONTROL OF WHITE PINE BLISTER RUST IN YELLOWSTONE NATIONAL PARK ;75 13y Clito E. Carlso.92 #,:,; g aj t.0 Vy qty; Co ABSTRACT Eradicatio of Ribes spp. to cotrol white pie blister rust i Yellowstoe Natioal Park was started i I 1968 this study was iitiated to evaluate the previous cotrol effort. Ribes eradicatio was suspeded i 1968 i 18 white pie stads ad Ribes ad rust were allowed to icrease withi rust cotrol uits. Eleve stads outside eradicatio uits were selected as checks. I 1968, ad agai i 1978, percet rust ifectio o pie ad the importace of Ribes were determied. Neither rust or Ribes icreased durig the 10-year period; both were essetially abset from the "eradicated" stads i 1968 ad Eve though Ribes populatios were comparatively high i the oeradicated stads, icidece of rust was early abset. The data show that the eradicatio of Ribes i Yellowstoe has had little or o effect o spread ad itesificatio of rust i the Park. INTRODUCTION Based o field studies that showed the ieffectiveess of Ribes spp. eradicatio for cotrol of white pie blister rust (Croartium ribicola J. C. Fisch.) o Natioal Forest lads of Regio. 1, the Forest Service discotiued its blister rust cotrol program i 1968 (Carlso ad Toko, 1968). However, Berg et al. (1975) poited out that ecological coditios i Yellowstoe Natioal Park are differet from orther Idaho ad may be limitig to 'rust spread ad itesificatio i the Park. Also, the eradicatio uits were much larger i Yellowstoe tha o the Natioal Forest ad the ifluece of uit size o rust

2 spread ad itesificatio may have bee differet tha i Idaho. Brow ad Carlso (1968), through the use of a cluster icidece survey, showed that rust levels were quite low i Yellowstoe eve i areas where Ribes populatios were high. Thus, the basic questio asked was, "Has the eradicatio of Ribes i Yellowstoe Park bee effective i limitig the spread ad developmet of blister rust?" METHODS Berg et al (1975) described the methodology for this evaluatio ad it is reviewed here. A area of 22,640 acres i the Mt. Washbur uit was eradicated of Ribes to a 0/0 stadard (0 Ribes ad 0 feet of live stem per acre) betwee 1968 ad Nie whitebark pie (Pius albicaulis Egel.) stads withi the area ad seve stads just outside the area were chose ad a cluster survey (Brow ad Carlso, 1968) to determie the proportio of pie stems ifected by rust was doe i each (figure 1). Subsequetly, the area withi the cotrol uit was ot reworked for Ribes for 10 years. At the ed of this period, i 1978, the cluster survey was applied agai i each stad. Ribes populatios were assessed by coutig the umber of Ribes ad estimatig the cubic foot volume of air space occupied by each plat o plots 66 feet log by 13.2 feet wide associated with each detailed tree. It was assumed i 1968 that durig the 10-year period 40 Ribes would icrease ad provide icreased substrate for the rust to complete its life cycle. Thus, rust theoretically should have icreased, 0 providig that ecological coditios were favorable. Besides the 16 stads associated with the Mt. Washbur area, 13 other whitebark pie stads, 9 of which had Ribes removed i 1972 ad 4 of which had o eradicatio history, were selected to expad the Washbur study. Evaluatio methods were the same as for stads i the Washbur uit. 4 Figure 1.--Mixed stad of whitebark pie ad subalpie fir. Mt. Washbur is i the backbroud. -2-

3 RESULTS AND DISCUSSION 41 Pertiet data are show i table 1. Rust icidece is expressed as proportio of pie stems ifected by rust ad Ribes populatios are give as a importace idex. Importace equals Ribes volume per acre multiplied 40 by frequecy. Frequecy was defied as the total umber of Ribes plats divided by the total umber of plots i the stad. A importace value of meas that o Ribes were foud. Blister rust was foud i oly two stads with a eradicatio history. Stad #8 at Carelia Creek had a PI (proportio ifected) of.01 ad stad #13 at Idia Creek had all.01 (i each of these stads, oly oe caker was foud). No rust was foud i the other 16 stads. Collectively, of early 10,000 trees observed, oly two were ifected. Similarly, i the stads that ever had bee worked for Ribes, oly two were ifected ad the of each was very low. StadA2 o Mt. Washbur had a pt of.05 ad stad #10 i Carelia Creek had a PI of oly Ribes spp. were foud i oly two stads with eradicatio history ad the importace values were low, 1.57 ad 0.01 i stads 8 ad 9, respectively. However, Ribes were foud i 6 of the 11 oeradicated stads ad importace values raged from 0.04 to The average PI for eradicated stads was i 1978 ad i 1968 ad the mea importace value for Ribes was Mea fr for oeradicated stads was i 1978 ad 4 i 1968 demostratig a very slight icrease over 10 years. Ribes, however, were fairly predomiat ad had a average importace of This compariso betwee eradicated ad oeradicated stads is show i figure 2. Clearly, it is show that the past effort to remove Ribes had little or o effect o white pie blister rust icidece. Rust ifectio has remaied very low eve though Ribes populatios were rather extesive i some of the oworked stads. The cause of low rust icidece must be related to idigeous ecological factors. The high elevatio stads (7,500 ft. m.s.l.+) aboud with Ribes motigeum, a relatively osusceptible host. Also, temperatures ad relative humidities may be adverse to rampat ad extesive exploitatio of whitebark pie by blister rust, which as poited out by Krebill 1/, simply caot occur. S CONCLUSIONS A beeficial effect of Ribes eradicatio i Yellowstoe Natioal Park has ot bee show. Rust icidece has remaied at very low levels eve though Ribes populatios were relatively extesive i some areas. Ecological coditios withi the Park probably limit rust spread quite effectively, eradicatio of Ribes clearly is ot warrated, ad the existece of white pie i the Park clearly is ot threateed by the rust. 1/ September 10, 1969, memoradum from Dr. Richard Krebill, Forest Service Research, to Mr. Bill Hedrickse of Yellowstoe Natioal Park. -3-

4 Table 1.--Rust ifectio ad Ribes importace for stads sampled. 41, Stad o. Locatio / PI- PI 1978 Cotrol Date last Ribes 2/ uit status Ribes importacel i/out removal Ifectio tred 1 Grebe Lake x Mt. Washbur x Mt. Washbur x Observatio Peak x Carelia Creek x Carelia Creek x Carelia Creek 0.01 x Obsidia Cliff x Idia Creek ,00 x Lewis Lake x Durave Peak 0.05 x Delacy Creek x Durave Pass x Pelica Creek x Elephat Back Mt. x Wolf Lake x Norris Jct. Ochre Sprig Mea.09 x x Mt. Washbur , x + 5 Mt. Washbur x 0 10 Carelia Creek x + 12 Observatio Peak 1.44 x 0 14 Lewis Lake x - 16 Durave Peak x 0 18 Lamar 7.24 x 0 19 Tower Creek x 0 20 Tower Creek x 0 21 Tower Creek x 0 23 Lewis Lake, x 0 Mea / PI Proportio of stems ifected by blister rust. 2/ Ribes importace = (Ribes vol/acre) x (total Ribes total plots sampled). S -4-

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6 V LITERATURE CITED Berg, M. J., C. E. Carlso, L. P. Lousbury, ad 0. J. poolig, Effectiveess of Ribes eradicatio i Yellowstoe Natioal Park. Study establishmet ad status report. USDA Forest Service Norther Regio. Uumbered report. Brow, D. H., ad C. E. Carlso, Blister rust icidece survey o whitebark ad limber pie, USDA Forest Service, Norther Regio. Uumbered report. Carlso, C. E., ad H. V. Toko, Prelimiary report - white pie blister rust icidece survey. USDA Forest Service Norther Regio. Uumbered report. ACKNOWLEDGEMENTS The assistace of Yellowstoe Park employees Mr. Gary Beale, Mr. Jim Sweay, ad their field crew is gratefully appreciated. Most of the field data was collected by them. -6-