Search Results
You are looking at 11 - 13 of 13 items for
- Author or Editor: D.P.H. Tucker x
Abstract
Three applications granular formulations of herbicides were applied broadcast over a 7-month period to budded citrus trees growing in 7.6 liters (4-gal) containers with a soil mix containing equal parts of peat, bark, and sand. Materials and rates at each application were alachlor + simazine 4.48 + 2.24 and 8.96 + 2.24 kg/ha; oryzalin 5.60 and 11.20 kg/ha; trifluralin 5.60, 11.20 and 22.40 kg/ha; oxadiazon 4.48 and 8.96 kg/ha; napropamide 11.20 and 22.40 kg/ha; and alachlor 11.20, 22.40 and 44.80. Good to excellent weed control was obtained at all rates of all herbicides used with no phytotoxicity to citrus trees observed.
Abstract
Microsprinkler irrigation was used to protect young citrus trees during severe advective freeze conditions in Florida during 24–26 Dec. 1983. Three factors (microsprinkler distance from the tree, compass position, and water volume output) influenced the amount of protection or tree damage. Spray jets that delivered 76 liters/hr (9 mm/hr) and were located 0.7 m or less from the north side of the trees protected the lower scaffold branches and trunk of young trees to temperatures below −6°C. Spray jet irrigation, particularly when jets were more than 1 m away on the east side of the trees resulted in more tree damage than no irrigation. This was due to low dew point temperatures and northwest winds which kept continuously-sprayed water away from the tree. Volume of water per tree needs to be moderately high, and spray jets should be located on the upwind (northwest) side of the tree at a distance no greater than 0.7 m from the tree in order to provide optimum freeze protection with microsprinkler irrigation.
A factorial experiment begun in 1980 included `Hamlin' and `Valencia' sweet-orange scions [Citrus sinensis (L.) Osb.], and Milam lemon (C. jambhiri Lush) and Rusk citrange [C. sinensis × Poncirus trifoliata (L.) Raf.] rootstocks, tree topping heights of 3.7 and 5.5 m, between-row spacings of 4.5 and 6.0 m, and in-row spacings of 2.5 and 4.5 m. The spacing combinations provided tree densities of 370, 494, 667, and 889 trees ha. Yield increased with increasing tree density during the early years of production. For tree ages 9 to 13 years, however, there was no consistent relationship between yield and tree density. Rusk citrange, a rootstock of moderate vigor, produced smaller trees and better yield, fruit quality, and economic returns than Milam lemon, a vigorous rootstock. After filling their allocated space, yield and fruit quality of trees on Milam rootstock declined with increasing tree density at the lower topping height. Cumulative economic returns at year 13 were not related to tree density.