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Plot Establishment (2002)
Seeds from a local milkweed population were germinated in the laboratory
and transferred to the greenhouse in mid-April. A preemergence
herbicide was applied and incorporated prior to manually transplanting the
50 - 100 ft² plots in late May 2002.
The within row plant distance was held constant at 8 inches. Plot
maintenance was done manually and pesticides were applied as needed to
control aphids. |
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Planting Density Trials
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Milkweed transplants were planted at 3 inter-row spacings
(7.5, 15, and 30 inches) to evaluate plant density and its effect on plant establishment
and follicle production. Three transplant initiation dates were also used
to determine whether first year follicle production is influenced by date of
seed germination. Seed was started March 15, April 1, and April 15.
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Nitrogen
Evaluations
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Nitrogen
at rates of 50 and 100 pounds per acre was applied to a number of
transplant plots to determine its effect on follicle production. All
nitrogen plots were planted at 15 inch inter-row spacing.
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Topping
Experiments
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A
selection of additional plots were kept pruned back to an 18 inch height
to evaluate the effects of first year topping on second year follicle production. All topping plots were planted at
15 inch inter-row
spacing. First Year Results (2002)
A small number of plants
produced follicles in the first year, but seed and floss was immature.
All stalks were removed at the end of the season.
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Maintenance (2003)
In advance of milkweed emergence in early spring, a
preemergence herbicide was applied to all plots. This application
provided good coverage for most weed species throughout the season with
remaining weeds controlled by hand cultivation or grass herbicide
application. Plants in all plots emerged by April 24 and began
blooming in early July. Nitrogen was reapplied to the nitrogen
evaluation plots on May 16. No additional pruning was performed on the
topping experiments this season. Spot treatments of aphids and black spot were performed
as needed. |
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Second Year Results (2003)
Follicles were harvested in mid-September when 10% of the
follicles were open. A total fresh weight of 450 pounds from 22,200
follicles was harvested from
all the plots combined. Nearly 4900 stalks of the 9950 stalks present
produced viable follicles. Results of the planting density trials
examining 3 inter-row spacings show that higher plant concentrations have an
adverse effect on follicle production. Evaluation of the 3 planting
dates demonstrated that the April 1 date produced the healthiest
plants at transplant time and again in 2003. In addition, topping the
milkweed did not influence follicle production in the second year. |
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