Susceptibility of Ponderosa Pine 

 to the Needle Cast Fungus 

 Lophodermium baculiferum 



R. J. Hoff 



INTRODUCTION 



In 1983, a small amount of needle cast was observed in 

 a plantation of ponderosa pine (Pinus ponderosa Laws.) in 

 northern Idaho. In 1984, the level of damaged needles had 

 increased, and by 1985 the damage had become severe. 

 The causal organism (Lophodermium baculiferum Mayr) 

 was identified by Sue Hagle, USDA Forest Service, North- 

 ern Region, Forest Pest Management, and John M. Staley, 

 Department of Pathology, Washington State University. 



Needle cast fungi can substantially decrease growth and 

 can also cause mortality, especially if the infection is of 

 current year's needles. Scots (Pinus sylvestris L.) pine 

 stands of central Europe have sustained heavy losses due 

 to L. pinastri (probably L. seditiosum) (Squillace and 

 others 1975). In North America the same fungus causes 

 downgrading and mortality of Scots pine (Merrill and 

 Kistler 1976; Skilling 1975; Skilling and Nicholls 1971). 

 Transfer of seed of populations of Scots pine with differ- 

 ing levels of susceptibility to L. pinastri (probably L. 

 seditiosum) has compounded this disease problem (Scholz 

 and Stevens 1982; Squillace and others 1975). 



The infection process or infection needs of L. baculi- 

 ferum are not known; neither is there any knowledge 

 concerning the genetics of resistance of ponderosa pine to 

 infection by this needle cast. However, data on and 

 evidence of resistance have been observed for several 

 other needle cast fungi. For example, Harvey (1976) 

 observed uninfected individuals within a provenance test 

 of ponderosa pine that were heavily infected with 

 Lophodermella morbida Staley & Bynum. Mitchell and 

 others (1976) reported resistant trees within a plantation 

 of Corsican pine (Pinus nigra var. maritinea [Acton] 

 Melville) infected by Lophodermella sulcigena (Rostr.) v. 

 Hohn. Hoff (1985) reported that the degree of susceptibil- 

 ity of lodgepole pine (Pinus contorta Dougl.) infected with 

 Lophodermella concolor (Dearn.) Darker was closely 

 associated with elevation of the seed collection; within- 

 family variability was also fairly high, yielding a family 

 heritability of 0.73. 



Conclusions from the large amount of literature on 

 resistance of Scots pine to Lophodermium needle casts in- 

 dicate that provenances differ in their response to infec- 

 tion (Baumanis and others 1982; Martinsson 1979), and 

 there is a relatively high within-provenance and within- 

 family variance for resistance (Martinsson 1979; Squillace 

 and others 1975). 



The purpose of this paper is to document the patterns of 

 variation of infection caused by L. baculiferum on ponder- 

 osa pine with respect to geographic area and elevation and 

 to document family variation. 



MATERIALS AND METHODS 



The Inland Empire Tree Improvement Cooperative has 

 established several plantations of ponderosa pine in 

 northern Idaho and western Montana. Trees in two 

 plantations— one a provenance test, the other a progeny 

 test— exhibited severe infection by L. baculiferum in 1985. 

 Infection appeared uniformly heavy over the entire planta- 

 tion, but there were scattered individuals throughout both 

 tests that were not infected. These were often surrounded 

 by severely infected trees. 



The two tests were planted side by side during spring 

 1974 at the Lone Mountain tree improvement site 25 miles 

 (40 km) north of Coeur d' Alene, ID, by the Northern 

 Region of the Forest Service. The site is flat, with only 

 slight undulations, at an elevation of 2,488 ft (758 m). The 

 entire 160-acre (65-ha) site is surrounded by naturally 

 regenerated ponderosa pine and lodgepole pine with a 

 lesser mixture of grand fir (Abies grandis [Dougl.] Lindl.), 

 Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] 

 Franco), and western larch (Larix occidentalis Nutt.). This 

 natural stand is two-layered with the overstory composed 

 of mature scattered trees (remnants of harvest) and the 

 lower layer composed of pole-sized trees 20 to 30 ft (6 to 

 9 m) tall. Most of these natural ponderosa pine were in- 

 fected with L. baculiferum to some degree. 



Provenance Test 



The seed came from 92 stands (populations) in north- 

 eastern Washington, north of the Salmon River in Idaho, 

 and western Montana (fig. 1). Open-pollinated seed was 

 collected from five individuals per stand and combined. 



The seedlings were grown at a Forest Service nursery 

 near Coeur d'Alene, ID, in nursery beds for 2 years, then 

 lifted and planted at the Lone Mountain tree improvement 

 site in April 1974. The experimental design was a ran- 

 domized complete block with 10 replications (blocks). Four 

 progeny of each stand were planted per replication as a 

 four-tree row plot. 



Data were taken by viewing the needles (those produced 

 in 1983) when the maximum expression of symptoms was 

 evident, from mid-May to mid-June of 1985. The damage 

 was evident as straw- to brown-colored needles. It was 

 assumed that the amount of this damage reflected infec- 

 tion severity. First, the entire plantation was observed for 

 20 to 30 minutes to get an idea of the general level and 

 range of infection. Then observers walked slowly along a 

 row of trees and placed each tree in one of the following 

 categories: 



1 



