Factors that are usually associated with the slowing of primocane growth during late summer hastened the appearance of floral primordia in red raspberry axillary buds. Of the factors tested, water stress was most effective in advancing floral primordia appearance. Small diam canes had buds more advanced than thick canes. July applications of succinic acid-2,2-dimethylhy dr azide (SADH) at 2000 and 4000 ppm and (2-chloroethyl)phosphonic acid (ethephon) at 500 ppm increased the number of blossom primordia present during early October. Growth regulators had no significant effect on yields.
Primocanes were sprayed after they reached about 18 cm in height with 4, 6-dinitro-o-sec-butylphenol (dinoseb) plus superior spray oil to kill the tops down to ground level. Additional treatments involved spraying after the second flush of growth reached 18 cm in height. Primocane suppression by this means increased yields by up to 70% over unsprayed plots. Plots of vigorous ‘Williamette’ raspberries (Rubus idaeus L.) were re-sprayed each year for 4 years and maintained the yield increase. A less vigorous ‘Sumner’ planting subjected to similar treatments did not develop adequate cane height and number after 2 or 3 sprays and yields the following year were greatly reduced. Berry size was sometimes increased. Most of the increased yields were due to greater numbers of berries. Primocane suppression had no effect on the number of berries on the upper laterals but greatly increased the numbers on laterals that developed from the middle and lower portions of the canes. The amount of carbohydrates per bud in dormant canes was reduced by dinoseb sprays applied the previous growing season.
In a 3-year study of ‘Willamette’ red raspberry canes the number of berries per lateral and the number of berries per cane were positively correlated with cane diameter. The number of fruitful nodes per cane was negatively correlated with cane diameter. Increased cane height caused more berries per lateral but the effect on number of berries per cane was minimal because of fewer fruiting laterals. The yield of ‘Puyallup’ was more adversely affected by reduced numbers of fruiting laterals than that of ‘Willamette’.
Higher topping increased the number of berries per cane by leaving more fruiting laterals. Berries per lateral was affected more by the amount removed in topping than by height of topping.
Cane diameter and height accounted for less than 25% of the variation in total berry production. Cane quality and other factors must also be considered in developing production practices for maximum yield.
Fruitfulness of individual red raspberry (Rubus idaeus L.) canes was increased by reduction of cane number per hill and by increase in cane diameter. Yield per hectare, however, was greatly increased by more canes per hill. Floral primordia bud number was more advanced in the fall on small-diameter canes, but the difference between small- and large-diameter canes disappeared by spring. Berry number and percentage fruit set were greater for large-diameter canes and were related to amount of available carbohydrate per node. Excessive moisture stress in late summer tended to delay carbohydrate build up.
‘Tempo’ bush beans (Phaseolus vulgaris L.) planted in rows spaced 12-inches apart yielded 64% more crop and had 64.4% more leaf surface per unit area than those planted in 36-inch rows. Row direction in relation to the prevailing wind had little effect on yields but a perpendicular arrangement caused lower relative humidity and higher air temperatures than parallel. Widening the row spacing increased the effect on relative humidity. Mist applications increased relative humidity and lowered air temperature.