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Charles J. Simon and John C. Sanford

A method is described for separating large and small pollen effectively from a heterogeneous mixture. This method potentially is applicable to separation of pollen grains of different ploidy levels, since “unreduced” 2n pollen is larger than normal pollen (n); it might then be used to increase the efficiency of a breeding program employing sexual polyploidization and to diminish crossing inefficiencies in interploid crosses.

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C.A. Weber, K.E. Maloney, and J.C. Sanford

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C.A. Weber, K.E. Maloney, and J.C. Sanford

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C.A. Weber, K.E. Maloney, and J.C. Sanford

The performance of 11 primocane fruiting raspberry (Rubus idaeus) cultivars was evaluated based on yield and fruit weight from the first three seasons compared to the eighth and ninth seasons, respectively. Plot vigor and cane density was evaluated in the eighth season. `Prelude', `Caroline', and `Heritage' did not show a decline in yield in the eighth season compared to the first three seasons. `Kiwigold', `Graton Gold' (sold as `Goldie'), `Watson' (sold as `Ruby'), `Autumn Bliss', `Anne, and `Amity' had substantial yield decreases from early production seasons ranging from -30% to -82%. `Kiwigold' had the highest yield of 4015 kg·ha-1 (3582.2 lb/acre) in the eighth season followed by `Caroline' at 3649 kg·ha-1 (3255.6 lb/acre), `Heritage' at 3614 kg·ha-1 (3224.4 lb/acre), and `Prelude' at 3591 kg·ha-1 (3203.9 lb/acre). Fruit weight did not vary significantly among years, but there were differences among cultivars. In the ninth season, `Ruby' had the largest fruit at 3.1 g (0.11 oz), followed by `Autumn Bliss' at 2.9 g (0.10 oz), and `Caroline' and `Prelude' at 2.8 g (0.10 oz). `Summit', `Goldie', and `Rossana' had the smallest fruit at 1.5 g (0.05 oz). `Goldie' was the most vigorous cultivar and `Anne' the least in the eighth season based on vigor ratings. `Rossana' had the highest cane density at 41.6 canes/m2 (3.86 canes/ft2). Seven of 11 cultivars had cane density of 32 canes/m2 (3.0 canes/ft2) or higher, which is sufficient to produce acceptable yields in cultivars suited to the region. Overall, `Prelude', `Caroline' and `Heritage' and its sports, `Kiwigold' and `Goldie', show the most potential for long production cycles in climates similar to western New York state.

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K.E. Maloney, W.F. Wilcox, and J.C. Sanford

`Titan' red raspberry (Rubis idaeus L.), highly susceptible to root rot caused by Phytophthora fragariae Hickman var. rubi Wilcox & Duncan (syns. P. erythroseptica Pethyb., “highly pathogenic” P. megasperma Drechs.), was planted in June 1990 in a silt loam naturally infested with the pathogen. Raked beds (0.36 m high) dramatically reduced disease incidence and severity relative to flatbed treatments. In contrast, metalaxyl at 372 mg·m-1 of row provided little benefit when applied to flat beds and provided consistently moderate but statistically insignificant effects when applied to raised beds. Relative to the flat bed system, primocane vigor was increased in 1992 by 16%, 190%, and 224% in the flat bed plus metalaxyl, raised bed, and raised bed plus metalaxyl treatments, respectively; total yields were increased by 7%, 231%, and 272% with these same respective treatment. The results indicate that raised-bed planting systems can provide substantial control of phytophthora root rot of red raspberries even when highly susceptible varieties are grown on otherwise marginal sites. Metalaxyl appears more effective as a supplement rather than substitute for raised beds under such conditions. Chemical name used: N- (2,6-dimethylphenyl) -N- (methoxyacetyl)alanine methyl ester (metalaxyl).

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C.M. Ronning, S.P. Kowalski, L.L. Sanford, and J.R. Stommel

The Colorado potato beetle is a serious pest of the cultivated potato. Natural resistance has been found in a few wild species, including Solanum chacoense Bitter, in which resistance is attributed to the presence of foliar specific leptine glycoalkaloids. Production and accumulation of these compounds within S. chacoense varies widely and appears to be inherited in a quantitative fashion, but high leptine producing clones occur rarely. In the present study, 15 different accessions from various locations and altitudes of origination were analyzed for foliar glycoalkaloid content in order to determine the frequency and distribution of genes for leptine production/accumulation, and to see if we could find a center, or core, of leptine production. Leptines were detected in eight of the 15 accessions, and the amounts within each accession varied widely, but none of the individuals produced high amounts of leptine (defined as greater than 62% of total glycoalkaloids). All of the leptine-containing accessions originated from western Argentina. There was no relationship between elevational level and leptine, but there was a negative trend with total glycoalkaloids and elevation; this was due to levels of solanine and chaconine decreasing with increasing elevation. In addition, nine unidentified glycoalkaloids were detected, in very high proportions in some individuals and accessions. AFLP marker frequency and diversity were used to compare subpopulations of these accessions. AFLP markers revealed substantial diversity among clones. The relationship of marker distribution to glycoalkaloid content is discussed. The results raise interesting questions about glycoalkaloid biosynthesis and inheritance, and point the direction for new avenues of leptine and glycoalkaloid research.

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A.R. Jamieson, N.L. Nickerson, C.F. Forney, K.A. Sanford, K.R. Sanderson, J.-P. Privé, and R.J.A. Tremblay

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A.R. Jamieson, N.L. Nickerson, C.F. Forney, K.A. Sanford, K.R. Sanderson, J.-P. Privé, R.J.A. Tremblay, and P. Hendrickson