Neil A. Anderson

THE GENETICS AND CULTIVATION OF PLEUROTUS OSTREATUS

Pleurotus ostrcatus has been shown to have a tetrapolar mating system with multiple factors at both the A and B series. Interstock dikaryons produced an average yield of 716.1 g of oyster mushrooms...

An assay to quantify vascular colonization of potato byVerticillium dahliae

A procedure was developed and tested to evaluate potato germ plasm for relative rates of vascular colonization byVerticillium dahliae. The number of colony forming units (CFU) per ml of plant sap, extracted from stems and plated on a medium, was used to assess vascular colonization from plants grown for 100 days in a field plot infested withV. dahliae. Sap extracted from main stem tissue at the ground line gave more CFU ofV. dahliae than tissue at the mid and apical region of the main stem. Aliquots of 0.05, 0.1 and 0.2 ml of plant sap were equally efficient in measuring vascular colonization. Thirty-three clones were evaluated for amount of vascular colonization in field and greenhouse tests with the former giving the best results. Cultivars and clones resistant to Verticillium wilt in Idaho, Maine, Minnesota, North Dakota and New York each had a low index of wilt and a low number of CFU/ml ofV. dahliae in plant sap in these tests. Clones intermediate in both wilt index and vascular colonization as well as selections with a high wilt index and extensive vascular colonization were found using the fresh sap assay method. Correlation values of, r = 0.92, r = 0.91 and r = 0.86 were observed between CFU/ml and percentage of foliar wilt for 11 clones/cultivars in 1986, 1987 and 1988, respectively. The correlation between CFU/ml and both moisture and temperature for the cultivars Kennebec and Russet Burbank, during a 6-yr period was r = 0.83.CompendioSe desarrolló y probó un procedimiento para evaluar germoplasma de papa para tasas relativas de colonización vascular porVerticillium dahliae. Se utilizó el número de unidades formadoras de colonias (UFC) por cm3 de savia, extraída de los tallos y depositada sobre un medio de cultivo, para determinar la colonización vascular de plantas mantenidas por 100 días en una parcela de campo infestada conV. dahliae. La savia extraída del tejido del tallo principal al nivel del suelo dio más UFC deV. dahliae que la procedente de los tejidos de las regiones media y apical del tallo principal. Alícuotas de 0,05, 0,1 y 0,2 cm3 de savia fueron igualmente eficientes en la medición de la colonización vascular. Se evaluaron 33 clones para cantidad de colonización vascular en pruebas de campo y de invernadero, obteniéndose en el campo los mejores resultados. Los cultivares y clones resistentes a la marchitez porVerticillium en Idaho, Maine, Minnesota, North Dakota y Nueva York tuvieron un bajo índice de marchitez y un número menor de UFC/cm3 deV. dahliae en la savia utilizada en estas pruebas. Utilizando el método de la savia fresca se encontre clones con un índice de marchitez y de colonización vascular intermedios al igual que selecciones con un alto índice de marchitez y una colonización vascular extensiva. Se observaron valores de correlación de r = 0,92, r = 0,91 y r = 0,86 entre el UFC/cm3 y el por ciento de marchitez foliar para 11 clones/cultivares, en 1986, 1987 y 1988, respectivamente. La correlación entre el UFC/cm3 y la humedad y la temperatura para los cultivares Kennebec y Russet Burbank, en un periodo de seis años, fue r = 0,83.

The Pleurotus Ostreatus-Sapidus Species Complex

SUMMARYTwo macroscopically indistinguishable, noninterbreeding populations of edible oyster mushrooms were studied. These were determined to be Pleurotos ostreatus which was found only on Populus t...

Early detection of Verticillium wilt resistance in a potato breeding program

Nine potato clones/cultivars selected for varying degrees of Verticillium wilt (VW) resistance based on degree of vascular colonization, were intercrossed and outcrossed to 13 uncharacterized clones. Based on growth characteristics of 3,535 seedling transplants and an assay quantifyingV. dahliae in potato vascular tissue, 404 clones were selected for further tests. The average number ofVerticillium dahliae colony forming units (CFU) expressed as Log10(CFU + l)/0.1 ml of plant sap for the 404 clones was 2.3, and 1.3 and 3.7 for resistant Reddale and susceptible Kennebec checks, respectively. Thirty-five clones (8.66%) had CFU values equal to or less than Reddale suggesting that VW resistance is a readily transmitted trait.CompendioNueve clones/cvs de papa, seleccionados por sus diversos grados de resistencia a la marchitez porVerticillium (VW) basados en el grado de colonizacion vascular, fueron retrocruzados y entrecruzados (menor parentezco) a 13 clones. Basándose en las características del crecimiento de 3 535 plántulas trasplantadas y en un ensayo cuantificativo deV. dahliae en el tejido vascular de la papa, se seleccionaron 404 clones para pruebas adicionales. El número promedio de unidades formando colonias deVerticillium dahliae (CFU), expresado como Log10(CFU + l)/0.1 cm3 de savia vegetal, para los 404 clones fue 2.3,y 1.3 y 3.7 para los testigos Reddale (resistente) y Kennebec (susceptible), respectivamente. Treinta y cinco clones (8.66%) tuvieron valores de CFU iguales o menores que Reddale sugiriendo que la resistencia a VW es un atributo transmitido rápidamente.

Biological Control of Septoria Leaf Spot Disease of Hybrid Poplar in the Field

Biological control of Septoria leaf spot of hybrid poplars was investigated using disease-suppressive Streptomyces strains. Field experiments were conducted in 1998 and 1999 on potted trees placed in a hybrid poplar plantation near Rosemount, MN, and on field-planted trees in 1998 at St. Paul. At both locations, one resistant and three susceptible hybrid poplar clones were sprayed with Streptomyces spore suspensions and exposed to natural field inoculum of Septoria musiva. In the 1998 potted-tree experiment, strains GS-93-3, 93, and Mycostop in Tergitol or Triton X-100 solutions applied every 7 days significantly reduced leaf disease by 29 to 83% compared with the controls. In the 1999 potted-tree experiment, Streptomyces strain mixtures in Tergitol solution applied every 5 days significantly reduced leaf disease by 50 to 87% compared with the controls. In the 1998 plantation experiment, strains GS-93-3, 93, or Mycostop in Tergitol solution applied weekly, bi-monthly, or monthly significantly reduced leaf disease in all treatments by 64 to 78% compared with the controls.

Field guide to common macrofungi in eastern forests and their ecosystem functions

Macrofungi are distinguished from other fungi by their spore-bearing fruit bodies (mushrooms, conks, brackets). These fungi are critical in forests, causing disease, and wood and litter decay, recycling nutrients, and forming symbiotic relationships with trees. This guide is intended to assist in identifying macrofungi and provide a description of the ecological functions of some of the most frequently encountered macrofungi in aspen-birch, northern hardwood, lowland conifer, and upland conifer forests in the Midwest and Northeast.

Interactions of insects, woodpeckers, and hypoxylon canker on aspen

Describes the disease history in two aspen plantations and the role of various wounds in the infection process.

Etiology of Bronze Leaf Disease of Populus

Bronze leaf disease is a potentially destructive disorder of the Populus section of the genus Populus. The causal agent has been reported to be Apioplagiostoma populi (anamorph: Discula sp.). Based on etiological and symptomological studies, field observations of symptom development suggest that the pathogen moves systemically in the host. This was verified by graft experiments where symptoms progressed from the scion into the elongating stem. A bronze-pigmented vascular discoloration was observed in symptomatic leaves and branches. Dieback of affected stems also was common. Spore-trap studies elucidated the timing and necessary weather conditions of A. populi ascospore dispersal in relation to infection and symptom development. Exposure-tree experiments revealed that ascospores of A. populi are the primary inoculum and resulting infection causes distinctive disease symptoms on affected trees. Perithecia of A. populi were observed on overwintered symptomatic leaves, but were not observed on asymptomatic leaves. Acervular conidiomata were observed on symptomatic leaves during August and September. Although A. populi ascospores germinated in vitro, A. populi was not recovered from symptomatic tissue. Isolations from diseased leaves consistently yielded Epicoccum nigrum, but the role of this species is unclear. Inoculations of susceptible plants with E. nigrum conidia failed to reproduce symptoms, but inoculations with ascospores of A. populi produced symptoms typical of bronze leaf disease and Kochs postulates were performed.

GENETIC VARIATION IN Gremmeniella abietina

Heterogenic incompatibility occurs in Gremmeniella abietina. Hyphal anastomosis occurred between European and North American isolates. Immunogenic tests of single ascospore cultures from a single apothecium collected in the field suggests hybridization between European and North American strains. Conidia produced from single ascospore cultures typing as either European or North American from the above apothecium, were used to inoculate seedlings of several species of pine, spruce, fir, larch, and Douglas-fir. Both strains infected all hosts, except that white fir was not infected by the European strain. The North American strain generally caused greater percent infection than the European strain.