By periodic sampling, seasonal patterns of the development of Fusarium root rot were studied in resistant and susceptible bean cultivars. Infection severity increased rapidly from the first sampling date, dropped off after the second or third, and again increased until the end of the season. In most cases, cultivar differences were apparent at any time after the second sampling, but resistant and susceptible cultivars could best be differentiated during the middle of the season. Sample variation was high, showing the potential for error in making single plant selections or in using small samples to compare cultivars.
Pea cultivars may be severely or mildly affected (susceptible), or completely symptomless (resistant) when infected with an Oregon isolate of PSV. Infected plants of susceptible and resistant cultivars contained substantial virus concentrations which were not consistently related to symptom severity. The severity of symptoms in inoculated plants and the numbers of plants showing symptoms differed in various tests, apparently in response to changes in environment and the virulence of the virus. When apparent maximum symptom expression occurred, it was shown that the highest degree of resistance was due to a single recessive gene. Deviations from the expected ratio of 3 susceptible: 1 resistant (symptomless) were always the result of excess symptomless plants, probably because of combinations of effects of the environment, modifying genes from one or both parents, and in the later phases of the study, a reduced virus virulence. Observations and limited tests suggested that symptom development was promoted by conditions which were unfavorable for optimum plant growth.
Commercial pea (Pisum sativum L.) cultivars, plant introduction (PI) lines, and Oregon State Univ. (OSU) breeding lines were tested for resistance to pathotype P2 (lentil strain) and pathotype P1 (type strain) of pea seedborne mosaic virus (PSbMV) and to bean yellow mosaic virus (BYMV) to assess the relative proportion of resistant and susceptible pea genotypes. Of the 161 commercial cultivars tested, 117 (73%) were resistant and 44 were susceptible to PSbMV-P2. Of these PSbMV-P2-resistant cultivars, 115 were tested for resistance to BYMV and all were resistant. Of the 44 PSbMV-P2-susceptible cultivars, 43 were tested for BYMV susceptibility and all were infected except two, `Quincy' and `Avon', both of which were susceptible to a BYMV isolate in another laboratory. Of 138 commercial cultivars inoculated with PSbMV-P1, all were susceptible. All PI lines and OSU breeding lines that were resistant to PSbMV-P1 were resistant also to PSbMV-P2. The high percentage of commercial cultivars resistant to PSbMV-P2 was probably attributable to the close linkage of genes sbm-2 and mo and the widespread use by breeders of BYMV-resistant `Perfection' and `Dark Skin Perfection' in developing new pea cultivars. Segregation ratios in progenies of three separate crosses between PSbMV-P2-resistant and PSbMV-P2-susceptible cultivars closely fit the expected 3 susceptible: 1 resistant ratio expected for resistance conferred by a single recessive gene.
The inheritance of resistance in beans (Phaseolus vulgaris L.) to typical bean yellow mosaic virus (BYMV) was compared to the severe strain (BYMV-S). When F3 families of BYMV resistant ‘Great Northern UI 31’ (GN31) × susceptible ‘Dwarf Horticultural’ were tested for resistance to each virus strain, occurrence of homozygous resistant families was conditioned by 3 recessive genes for BYMV and 2 recessive genes for BYMV-S. Of the 132 families tested, 122 were susceptible to both BYMV and BYMV-S, 6 were resistant to BYMV-S and susceptible to BYMV, 4 were susceptible to BYMV-S and resistant to BYMV, and none were resistant to both. This ratio closely fits a theoretical 945:63:15:1, indicating that resistance to BYMV and to BYMV-S are inheritied independently. When GN31 was crossed with breeding line Sl-5, also resistant to both virus strains, F3 progenies included families susceptible to one or both virus strains, possibly through the complimentary interaction of modifiers. Chi square tests indicated independent inheritance of resistances to BYMV and BYMV-S in GN31 × S1-5 progenies.
Globe artichokes (Cynara scolymus L.) were grown from seed in the greenhouse and transplanted to the field in 1978, 1979, and 1980. Percentage of flowering without artificial vernalization of the transplants was 75%, 92%, and 99% for the 3 years. Nitrogen sidedress applications above a base rate of 48 kg N/ha did not significantly increase weight or number of buds per plant or buds/ha. Plant spacing of 1 × 0.6 m generally increased total weight and number of buds/ha, but reduced number and weight of buds/plant compared to spacings of l × lmorl × 2m. Average weight/bud was unaffected by either nitrogen level or plant spacing. Total yield was similar to California production of clonally produced artichokes, but buds were smaller.
Incidence of head smut caused by Sphacelotheca reiliana (Kuhn) Clinton in sweet corn (Zea mays L.) was decreased by frequent early irrigation (total of 15-20 cm of water during the first 18 to 21 days after planting), compared to no irrigation during the same period. The percentage of infection increased as planting depth increased from 2.5 cm to 7.6 cm. Large seed produced fewer infected plants than small seed, whereas the percentage of infected plants produced from medium-size seed was intermediate.
Wider spacing and fertilizer application increased the weight of both axillary heads (AH) and main heads in an open-pollinated cultivar and an inbred line. AH weight increased more than main head weight. The effect of spacing on AH was greater than that of fertilizer application. Transplanting greatly decreased the development of axillary heads when compared with direct-seeding.
‘Oregon 17’ is an early maturing bush green bean of ‘Blue Lake’ pod type. Its use may permit an earlier beginning of operations by Oregon processors. ‘Oregon 17’ is about two days earlier than ‘Oregon 1604’, a standard cultivar for commercial canners in western Oregon. ‘Oregon 17’ should yield less than ‘Oregon 1604.’ However, this deficiency may be offset by greater processing efficiency of ‘Oregon 17’ pods, which are smoother and straighter than those of ‘Oregon 1604’.
‘Oregon 83’ is a bush green bean developed for commercial processing in western Oregon, where beans of the ‘Blue Lake’ type, either bush or pole, have been important for about 50 years. ‘Oregon 83’ is generally ‘Blue Lake’ in foliage and pod characteristics (Fig. 1). It may supplement or partially replace ‘Oregon 1604’, a high yielding cultivar from the Oregon State University breeding program. Compared to ‘Oregon 1604’, ‘Oregon 83’ is slightly later, has a shorter, straighter pod, and better growth habit. The medium-length, generally straighter pods should facilitate more efficient processing.
‘Oregon 91’ is a bush green bean developed for commercial processing in western Oregon. It results from 22 years of breeding to develop bush bean cultivars with pod characteristics of ‘Blue Lake’ pole bean and an acceptable growth habit. ‘Oregon 91’ should complement or partially replace ‘Oregon 1604’, a bush green bean of ‘Blue Lake’ type which has been important to Oregon processors because of its earliness and dependable production. Compared to ‘Oregon 1604’, ‘Oregon 91’ is slightly later in maturity and slightly less productive, but has a better growth habit and straighter pods. It should be most useful to processors who need pods of smaller diameter than those of ‘Orergon 1604’.