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  • Author or Editor: Donn T. Johnson x
  • Journal of the American Society for Horticultural Science x
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Thorny erect blackberries (Rubus spp.) were evaluated for yield and cane vigor as affected by galls produced by the rednecked cane borer Agrilus ruficollis (F.). Galling in `Cherokee' significantly (P < 0.001) decreased the count of berries and the weight of berries per centimeter of live cane. Winter injury, water stress, and nutritional stress induced by galls increased the amount of dead wood per cane. Galling did not affect the length of live laterals per `Cherokee' cane. For `Comanche' and `Cheyenne', the amount of dead wood per cane increased as gall counts increased. In contrast, the length of live laterals per cane increased for `Comanche' and decreased for `Cheyenne' as gall counts increased. The weight of berries and the count of berries per centimeter of live cane for `Comanche' and `Cheyenne' were not related to the count of galls. Of the four cultivars, `Shawnee' produced the most berries and greatest weight of berries per centimeter of live cane when canes were free of galls. Conversely, when galls exceeded two per cane, `Shawnee' yielded least, followed by `Comanche', `Cheyenne', and `Cherokee'.

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A computer simulation of asparagus growth is developed and used to evaluate the effects of various harvest strategies on short and long term commercial yield of asparagus (Asparagus officinalis L.). At present asparagus is harvested until the canners stop buying, usually in the 3rd or 4th week of June in southern Michigan, purchase generally being terminated by the reduction of spear diameter (whips), increase in fiber content of the spears or opening of the bracts. The simulation shows that this stragety is economically optimal for any single year; however, if the grower terminates the harvest every year on June 1, then the average yearly yields are significantly greater than those derived from the previous strategy. Skipping strategies, in which the grower skips a harvest every nth year (2nd, 3rd, or 4th), produced significantly lower 15 year average yields than either of the other 2 strageties, but produced significantly greater yields per plant.

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