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Field experiments were conducted with Cucurbita pepo L. `Howden' pumpkin in 2000 to 2001 to study the effects of silicon (Si) amendment of soil with and without the use of fungicides on yield and powdery mildew suppression. A Quakertown silt loam soil (fine-loamy, mixed, mesic Typic Hapludult) with an initial soil pH of 5.7 was amended with either CaCO₃ or CaSiO₃ at the rate of 7840 kg·ha^-1 of calcium carbonate equivalent. Fungicides were applied on a 7-10 day schedule to half of the plots as a 2 × 2 factorial, beginning when the first powdery mildew lesions were detected in the field. Silicon amendment increased pumpkin yield by 60% in 2000 but Si did not influence yield in 2001. Infection with bacterial leaf spot reduced yield on all plots in 2001. Fungicide applications increased yield only in 2001. In 2000, Si amendment had the effect of delaying foliage senescence but it was not clear if this was the result of an effect of Si on disease activity or crop physiology. In Aug. 2001, Si amendment generally reduced powdery mildew severity, but only at the 10% level of significance. In Sept. 2001, the combination of Si amendment plus fungicide application was more effective in reducing powdery mildew severity than either Si or fungicide alone. Silicon amendment resulted in a 5-fold increase in plant Si concentration. Soil pH measured after harvest in 2001 indicated no significant difference in pH between plots amended with CaCO₃ (pH = 6.8) and CaSiO₃ (pH = 6.9). In New Jersey, the cost of these liming materials is similar. Thus, the selection of CaSiO₃ as a liming material as needed for soil pH correction has the potential benefits of suppressing powdery mildew and increasing pumpkin yield without increasing the cost of production.

The use of highly feathered trees can make high-density apple plantings more profitable through enhanced precocity and increased early yield. Currently, nurseries are asked to provide highly feathered trees with wide branch crotch angles. The use of plant growth regulators (PGRs) can play a key role when it comes to branch induction; however, dose and timing both need to be tested to enhance branching without compromising other tree quality attributes. Over the last 4 years, we have conducted studies of the use of MaxCel^® (6-benzyladenine) and Promalin^® (a mixture of 1.8% 6-benzyladenine and 1.8% GA₄₊₇) in comparison with Tiberon™ SC (cyclanilide) at several nurseries in NY, WA, DE, Ontario (Canada), and Chile. The best results were obtained with four applications of MaxCel^® or Promalin^® (400 mg·L⁻¹) beginning when leader growth reached 70 cm above the soil line and reapplied at 10–14 days intervals. Promalin^® was a slightly less effective branching agent than MaxCel^®. On the other hand, Promalin^® stimulated leader growth resulting in improved final tree height, whereas MaxCel^® induced the widest branch angles. Overall, we observed good response and quality ratings with ‘Cameo’, ‘Cripps Pink’, ‘Enterprise’, ‘Fuji’, ‘Ambrosia’, ‘Crimson Crisp’, ‘Gingergold’, and ‘Granny Smith’, whereas less quality ratings were observed on ‘Ambrosia’, ‘Cortland’, ‘Goldrush’, ‘Honeycrisp’, and ‘Suncrisp’. Response with ‘Gala’ varied depending on the temperature range. Multiple sprays of Gibberellins (GA₄₊₇, or GA₃) at 250 mg·L⁻¹ applied to nursery trees in the late summer inhibited flower bud development and flowering in the orchard the next year. This reduces the risk of fire blight infection in newly planted trees.