Two field experiments were conducted to assess peach (Prurus persica L.) cultivar susceptibility to the three Botryosphaeria spp. that cause peach tree fungal gummosis. Inoculated trees were evaluated for disease severity by rating gum exudation, vascular discoloration, and fungal colonization. Each severity measurement yielded a different rank ordering of cultivars for susceptibility. However, in a greenhouse study, these same measurements gave consistent rankings for aggressiveness of the fungal species on `Blake'. Despite large differences in disease severity in the greenhouse study, none of the severity measures were correlated with tree growth after inoculation. The only factor significantly correlated with growth rate of the trees after inoculation was growth rate before inoculation.
K.O. Britton, F.F. Hendrix, P.L. Pusey, W.R. Okie, C.C. Reilly and J.W. Daniell
Sarah J. Pethybridge, Niloofar Vaghefi and Julie R. Kikkert
trial was conducted twice. Disease severity was assessed by counting the number of CLS lesions on each plant and calculating the average number per leaf. Disease assessments were conducted at 6, 10, 13, and 17 d after inoculation (DAI) and used to
G. Jung, J. Nienhuis, S. Hirano, C. Upper, H. Ariyarathne and D.P. Coyne
Bacterial brown spot (BBS), incited by the bacterial pathogen Pseodomonas syringae pv. syringae is important disease of common bean. Phenotypic visual readings of infected areas and a leaf freezing assay estimating the population size of Pss on leaf surface were used for disease assessment for 2 years using 78 RI lines derived from Belneb RR-1 x A55 population grown in Wisconsin. The objectives of this research were to determine the genomic regions of QTL affecting the genetic variation of bacterial brown spot resistance in both assays over 2 years (1996 and 1998) and to determine the size of their genetic effects. In addition, we examined the consistency of detected QTL over environments. Three chromosomal regions associated with QTL for BBS resistance were identified in both assays in 1996 and one chromosomal region was consistently detected over 2 years.
Doug Sanders, Luz M. Reyes, David Monks, Frank Louws and James Driver
We evaluated the influence of three compost sources and compost amended with T382 with fumigant Telone C-35 and various combinations of compost and Telone C-35 on the yield and pest management of cucumber, pepper, tomato, collard, southern pea, and summer squash in a multicrop rotational system. In the first year, there were few differences between the compost treatments and Telone C-35, but all treatments resulted in more yield than the control. In the second year, all compost treatments and/or Telone C-35 improved total and marketable yield of cucumber, pepper, tomato, southern pea, and summer squash. Furthermore, in the second year, Telone C-35 treat-ments produced more yield than some of the compost treatments in tomatoes. Combining Telone C-35 with compost did not differ from either treatment alone. Nematode and disease assessments were not consistent and will be discussed in further detail.
Bruce W. Wood, Charles C. Reilly, Clive H. Bock and Michael W. Hotchkiss
The economic cost of pecan scab, caused by Fusicladium effusum G. Winter, can substantially limit profitability of pecan [Carya illinoinensis (Wangenh.) K. Koch] cultivation in humid environments. Laboratory, greenhouse, and field studies found nickel (Ni) to inhibit growth of F. effusum and reduce disease severity on fruit and foliage of orchard trees. Nickel was toxic to the fungus in vitro at concentrations applied to orchard trees, and Ni sprays reduced scab severity on foliage of pecan seedlings in greenhouse experiments. Host genotype appears to influence Ni efficacy with fruit tissue of cultivars of intermediate resistance (i.e., ‘Desirable’) being most responsive to treatment and those most susceptible to scab (i.e., ‘Wichita’ and ‘Apache’) being least responsive. Addition of Ni as a nutritional supplement applied in combination with fungicides applied as air-blast sprays to commercial orchards reduced severity of scab on both leaves and fruit depending on cultivar and date of disease assessment (e.g., scab severity on fruit was reduced by 6% to 52% on ‘Desirable’ in an orchard setting). Nickel-supplemented fungicide sprays to ‘Desirable’ trees in commercial orchards also increased fruit weight and kernel filling, apparently from improved disease control. Although the efficacy of Ni was typically much less than that of triphenyltin hydroxide (TPTH), a standard fungicide used in commercial orchards, Ni treatment of tree canopies for increasing tree Ni nutrition slightly lowered disease severity. These studies establish that foliar Ni use in orchards potentially reduces severity of scab on foliage and fruit in scab-prone environments. The inclusion of Ni with fungicides for management of pecan scab might reduce disease severity over that conferred by fungicide alone, especially if targeted cultivars possess at least a moderate degree of scab resistance. Similar benefit from Ni sprays might also occur in host–fungi interactions involving other crops.
Nancy G. Creamer, Mark A. Bennett, Benjamin R. Stinner and John Cardina
the USDA Sustainable Agriculture Research and Education Program, the Mid-America Food Processors Association, and Virginia Stranahan. We extend our appreciation to Mac Riedel and Debbie Hamner, who assisted with disease assessment, and to Barry
Ariadna Monroy-Barbosa and Paul W. Bosland
development everyday after inoculation with the earliest symptoms appearing 2 d after inoculation. The plants were removed from the mist chamber, placed on a bench, and scored once the susceptible control ‘Camelot’ displayed a disease assessment level of 5
Gabriele Gusmini, Luis A. Rivera-Burgos and Todd C. Wehner
( Gusmini and Wehner, 2002 ; Song et al., 2004 ), including systems for mass production of inoculum of S. cucurbitacearum for large field screening experiments ( Gusmini et al., 2003 ), and a disease assessment scale for rating foliar and stem lesions
Melinda A. Miller-Butler, Barbara J. Smith, Kenneth J. Curry and Eugene K. Blythe
plant disease response to be determined without destroying the plant, reduces the time between inoculation and disease assessment, and confines the pathogen to the laboratory, which allows breeders to test for pathogens or races of pathogens from other
Ken Obasa, Jack Fry and Megan Kennelly
distribution. After ≈14 d of incubation, the infested oat kernels were used, without drying, for inoculation of established progeny turfgrasses in pots and in the field. Growth chamber studies Plant inoculation and disease assessment. Stolons of the 14 new