Search Results
You are looking at 1 - 6 of 6 items for :
- Author or Editor: M. Warmund x
- HortScience x
Abstract
An oat (Avena sativa L. ‘Otee’) cover crop was planted in nursery beds seeded with Acer ginnala Maxim., Celastrus scandens L., and Elaeagnus angustifolia L. and 21 Mar. 1985. Postemergence graminicide treatments were applied on 25 Apr. and 8 May after the nursery seedlings had germinated and when the oats were ≈15 and 38 cm tall. Treatments included fluazifop at 0.28, DPX-Y6202 at 0.11, haloxyfop at 0.28, and sethoxydim at 0.34 kg·ha-1. In 1986, the same herbicides, except DPX-Y6202, were applied alone to Sophora japonica L. seedlings grown in an oat cover crop. Six days later, imazaquin at 0.14 kg·ha1 or chlorimuron-ethyl at 0.009 kg·ha1 was applied alone and to plots that had previously received graminicide treatments. Acer and Celastrus seedlings in plots treated on 25 Apr. 1985 had greater dry weight than those treated on 8 May 1985. Date of herbicide treatment did not affect the dry weight of Elaeagnus seedlings. In 1986, graminicides provided complete control of oats, but broadleaf weed growth was subsequently released. Imazaquin and chlorimuron-ethyl provided control of pigweeds (Amaranthus sp.), but did not control lambsquarter (Chenopodium album L.) or purslane (Portulaca oleracea L.). Tree seedlings treated with haloxyfop alone, sethoxydim alone, or sethoxydim plus imazaquin had greater dry weight than those in the untreated controls. DPX-F6025 alone reduced seedling dry weight when compared to that of the untreated control. Chemical names used: (±)-2-[4[[-5-(trifluoromethyl)-2-pyridinyl)oxy]phenoxy] propanoic acid (fluazifop); (±)-2-[4-[(6-chloro-2-quinoxalinyl)oxy]phenoxy] propanoic acid (DPX-Y6202); 2-[4-[[3-chloro-5-trifluoromethyl)-2-pyridinyl]oxy]phenoxy] propanoic acid (haloxyfop); 2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one (sethoxydim); 2-[4,5-dihydro-4-methyl-4-(1-methylethyl) 5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid (imazaquin); 2(([(4-chloro-6-methoxypyrimidine-2-yl)amino carbonyl]amino sulfonyl))benzoic acid, ethyl ester (chlorimuron-ethyl).
`Danka' black currant floral buds produce multiple low temperature exotherms (LTEs). However, the absence of visual injury symbtoms in the buds after exposure to subfreezing temperatures make it difficult to assess injury in these buds. A 2,3,5-triphenyltetrazolium chloride (TTC) reduction assay was used to determine whether LTEs corresponded to freezing injury of individual floral primordia or to the entire floral axis. Intact buds were cooled at 3C/n, removed at 3C intervals from -12 to -33C, and thawed on ice for 24 h. Duplicate samples were subjected to differential thermal analysis. Freeze injury Could not be measured with TTC in thawed, intact buds. However, incubation of excised floral primordia in TTC resulted in an all or nothing response. The number of LTES did not correspond to the number of floral primordia killed within a floral bud, but the median LTE did correspond with the temperature at which lethal injury of the whole inflorescence occurred. Therefore, preliminary results indicate that TTC reduction assay of individual floral buds is a fast, reliable technique to assess bud injury.
Abstract
Flurprimidol and XE-1019, applied at 15.0 and 2.5 mg/plant respectively, suppressed shoot dry weight and increased xylem pressure potential of Forsythia spectabilis Spaeth when drought was induced but did not affect leaf size or root dry weight. XE-1019 did not suppress growth when applied on 28 Aug. 1985. Plants treated with flurprimidol in late August had less shoot growth and higher xylem pressure potential than untreated controls or plants treated with XE-1019. Mefluidide applied as a foliar spray at 5000 mg·liter-1 on 25 June 1985 did not suppress growth or affect plant moisture status of forsythia. None of the growth regulators reduced the transpiration rate of forsythia plants. Chemical names used: N-[2,4-dimethyl-5-[[(trifluoromethyl) sulfonyl]amino]phenyl]acetamide (mefluidide); α-(1-methylethyl)- α-[4-trifluoromethoxy)phenyl]-5-pyrimidinemethanol (flurprimidol); (E)-(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (XE-1019).
Abstract
Chlorsulfuron was applied alone at 0.018 kg·ha−1 and in combination with 3.4 kg·ha−1 of oryzalin at rates of 0.018, 0.035, 0.070, and 0.140 kg·ha−1 to a mature ‘Chancellor’ grape (Vitis × sp.) vineyard. Oryzalin was also applied alone at 3.4 kg·ha−1. Oryzalin plus chlorsulfuron treatments provided excellent weed control. The vegetative growth of vines was reduced in the oryzalin plus chlorsulfuron treatments at rates of 0.07 and 0.14 kg·ha−1 as compared to the control. Oryzalin used alone and oryzalin plus chlorsulfuron used at the lowest rate were the only treatments that did not adversely affect vine growth or fruit quality. Chemical names used: 2-chloro-N-[[(4-≎ methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide (chlor-sul-≎ furon); 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin).
Rhizomes of zoysiagrass (Zoysia spp.) were subjected to controlled freezing tests in Jan. and Mar. 1993 and 1994 to determine their low-temperature tolerance. In 1994, `Belair', `Korean `Common', `Meyer', and `TGS-W10' rhizomes survived temperatures as low as -18 °C, while rhizomes of `Sunburst' survived -14 °C. `Cavalier', `Crowne', `Palisades', `Emerald', and `El Toro' were killed at -10 °C or warmer temperatures. Entries surviving exposure to -14 to -18 °C in 1994 controlled freezing tests received post-winter survival ratings in the field of 6.7 to 8.7 (9 = 100% green). Entries killed at higher freezing test temperatures were slower to recover after winter in the field, with ratings of 2.0 to 3.0. Shoot number produced after freezing was a better measurement for assessing low temperature tolerance than was shoot mass. Controlled freezing tests, using regrowth as a measure of hardiness, appear to be useful for identifying low temperature tolerance of zoysiagrasses in the early years of a field study.