Showing papers by "Michael J. Wingfield published in 1987"

Fungi associated with the pine wood nematode, Bursaphelenchus xylophilus, and cerambycid beetles in Wisconsin

Abstract: The pine wood nematode, Bursaphelenchus xylophilus (Steiner and Buhrer) which is carried by cerambycid beetles (Coleoptera: Cerambycidae) causes a serious disease of native pines in Japan. Details of the life cycle of B. xylophilus, and the associated disease cycle have been presented in a number of recent reviews (Mamiya, 1976, 1983). The nematode was first found in the United States in 1931 (Steiner and Buhrer, 1934; Nickle et al., 1980) and subsequently recognised as a pathogen (Dropkin and Foudin, 1979). Bursaphelenchus xylophilus is mycophagous (Kobayashi et al., 1974) and has apparently become adapted to feeding on living pine tissue. In Japan, some fungi associated with B. xylophilus in dying pines have been identified. In the United States, however, little attention has been given to the fungi associated with the nematode. The aim of this study was to identify fungi from the pupal chambers of cerambycid beetles in pine wood nematode infested trees, from the nematodes themselves and from cerambycid beetles emerging from the trees. The role of these fungi in the ecology of B. xylophilus is considered. Twenty-year-old jack (Pinus banksiana Lamb) and red pines (P. resinosa Ait.), occurring at Black River Falls, Jackson Co., Wisconsin, were selected for study. Five trees of each species infested with B. xylophilus and cerambycid beetles were felled and cut into 60 cm bolts. Jack pine trees had died after being artificially girdled in a previous study (Wingfield, 1982) and the red pines had died due to fire scorching and subsequent infestation of Dendroctonus valens (Le C.) (Wingfield, 1983). Pine bolts were transported to Minnesota where cerambycid beetle pupal chambers (64 from red

Pathogenicity of Bursaphelenchusxylophilus on three species of pine

Abstract: Three species of 11-year-old pine trees were inoculated with Bursaphelenchusxylophilus in the field. Four branches in single whorls on red, Scots, and jack pine trees were wounded and inoculated with 10 000 nematodes each or with water extracts from Botrytiscinerea cultures. Prior to field inoculations, the pathogenicity of the nematode isolate was confirmed on seedlings in the greenhouse. Fourteen weeks after inoculation, 27 of 80 and 13 of 52 branches were dead or dying on Scots and jack pine trees, respectively. No symptoms were observed on red pine trees inoculated with B. xylophilus or on any controls. Branch death was attributed to the formation of girdling cankers resulting from inoculation. An average of 9.14, 10.39, and 0.02 nematodes were extracted per gram of wood from branch samples collected from Scots, jack, and red pine trees at 14 weeks, respectively, and at 58 weeks an average of 13.82, 1.01, and 0.05 nematodes per gram of wood sampled were recovered. Proportions of branch samples with ne...

Selective medium for isolating Sphaeropsis sapinea

Abstract: Swart, W. J., Wingfield, M. J., and Knox-Davies, P. S. 1987. Selective medium for isolating Sphaeropsis sapinea. Phytopathology 77:1387-1389. Seventeen fungicides were tested in vitro for their effect on the growth of selective medium comprising Difco agar (20 g/ L), Difco malt extract (10 Sphaeropsis sapinea. Ten were selected for further evaluation on 14 g/L), rose bengal (50 /tg/ml), benodanil (10 Mg a.l./ml), chlorothalonil contaminant fungi commonly associated with S. sapinea in host tissue. (I gg a.i./ml), and o-phenylphenol (l/ig a.i./ml) was more effective for Benodanil and rose bengal suppressed all test fungi more than S. sapinea. isolating S. sapinea from woody tissue than malt extract agar (M EA) alone, Chlorothalonil and o-phenylphenol were the most effective inhibitors of or a previous MEA medium containing tannic acid. Trichoderma sp. and Mucor sp., the two fastest-growing contaminants. A Additional key words: Diplodia pinea, Pinus spp. Sphaeropsis sapinea (Fr.) Dyko & Sutton (Diplodia pinea Griff. & Maubl., Cytospora sp., Sclerophoma pythiophila (Cda.) (Desm.) Kickx) is a serious pathogen of pines in many countries Hbhn., Curvularia sp., Rhizoctonia solani KUhn, and Mucor sp. (1,4,7). Attempts to isolate the pathogen from host tissue are often They were grown on M EA plates for 3 days at 25 C. A 5-mm plug impeded by fast-growing fungal contaminants. Vaartaja (10) used of each fungus was then transferred from the periphery of the a malt-extract agar (MEA) medium containing tannic acid to colony to each of five plates containing the compound to be isolate S. sapinea (as Macrophoma sapinea (Fr.) Petrak) from pine screened. Colony diameters were recorded after 72 and 144 hr at 25 wood. We found Vaartaja's medium to be unsatisfactory because C, as the mean of two measurements perpendicular to each other. the tannic acid did not inhibit common contaminants sufficiently, Comparative efficiency of combined fungicides. Compounds and it softened and discolored the medium, either selective toward S. sapinea or highly inhibitory toward the This paper describes a selective medium for the isolation of S. fastest-growing fungi, especially Trichoderma sp., were combined sapinea from diseased pine roots and tissue infested with pine in various concentrations in selective media and tested with S. insects and compares it with a nonselective medium and one sapinea and the 14 test fungi. Colony diameters were measured on containing tannic acid. the selective media, MEA, and the tannic acid medium (TAM). To verify the efficacy of the final selective medium (SM), MATERIALS AND METHODS recovery percentages of S. sapinea from naturally infected and artificially inoculated host tissue were calculated. Pine needles and Screening fungicidal activity. Seventeen fungicides (Table 1) 25-mm-long stem sections from I-yr-old Pinus radiata D. Don were assayed for their effect on the radial growth of S. sapinea, seedlings were autoclaved, placed on water agar that had been with each compound being tested at concentrations of 0. 1, 0.5, 1, 5, inoculated with S. sapinea, and incubated at 25 C for 30 days. The 10, 50, 100, and 500 Mg a.i./ml. The basal medium (MEA) consisted of 10 g of Difco malt extract, 20 g of Difco Bacto agar, and I L of deionized water. The medium was cooled to 50 C and TABLE 1. Effects of different fungicides on the growth of Sphaeropsis amended with appropriate volumes of a stock solution of each sapinea' fungicide. The unamended MEA medium served as the control. Lowest concentration Media were agitated for 2 min before approximately 20 ml of each causing> 50% medium was poured into each .of five 90-mm petri dishes. Plates reduction of growth % Inhibition were inoculated with 5-mm disks from the periphery of a 3-day-old Compound (Ag a.i./ ml) of S. sapinea' M EA culture of S. sapinea (PREM 48859-National Collection of Benomyl 0.1 98.90 Fungi, Pretoria). Plates were incubated at 25 C and the colony Tridemorph 0.1 65.13 diameters (mm) were recorded after 92 hr as the mean of two Etaconazole 0.5 88.12 measurements taken perpendicularly to each other. Each test was Propiconazole 0.5 87.88 conducted twice. Cycloheximide 0.5 52.78 Suppressing contaminant fungi. During the preliminary tests 10 Iprodione 1 81.26 compounds had an inhibitory effect on S. sapinea only at Imazalil 1 67.30 concentrations greater than I )ug a.i./ml (Table I). These were o-Phenylphenol 5 70.62 further screened at specific concentrations to determine their effect Chlorothalonil 5 50.32 on 14 fungi commonly occurring together with S. sapinea in host Mancozeb 10 51.22 tissue. The test fungi were: Ceratocystis ips Rumbold, Copper oxychloride 50 98.30 ' a tab 50 60.00 Leptographium serpens (Goid.) Siem., Trichoderma sp., Benodanil 50 65.79 Cladosporium sp., Penicillium sp., Pestalotiopsis sp., Gliocladium Rose bengal 100 83.78 roseum Bain., Pestalotia sp., Lasiodiplodia theobromae (Pat.) Zineb 500 60.92 Novobiocin 500 95.74 Streptomycin >500 -'Colony diameter on malt-extract agar (M EA) after 92 hr incubation at 25 C. ©1987 The American Phytopathological Society bReduction in colony diameter compared with M EA. Vol. 77, No. 10, 1987 1387