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- Author or Editor: John C. Williams x
- HortScience x
Abstract
Cuttings of poinsettia (Euphorbia pulcherrima Willd.) treated with a basal dip of 0.1% indolebutyric acid (IBA) alone (control) or in combination with 5% ferbam (ferric dimethyldithiocarbamate), benomyl [methyl 1-(butyl-carbamoyl)-2-benzimida-zole-carbamate], metalaxyl [N-(2,6-dimethylphenyl)-N-(methoxyacetyl) alanine methyl ester], PCNB (pentachloronitrobenzene), and ethazol (5-ethoxy-3-tricloromethyl-l,2,4-thiadiazole) did not differ in rooting index or weight. Increasing the percentage of fungicide above 5% generally reduced rooting. However, rooting was similar to the control with combinations of ferbam at 5% to 67% or metalaxyl at 20%. Fenaminosulf (p-dimethylaminobenzenediazo sodium sulfonate) at 5% to 67% reduced rooting.
Abstract
A container growing medium of 2 peat : 1 perlite (v/v) was limed with 0, 0.9, 1.8, 2.7, 3.6, 5.4, 7.2, and 9.0 kg·m–3 dolomite. Media were irrigated with water, providing alkalinity equivalent to 0, 38, and 371 mg·liter–1 CaCO3. Samples were incubated at 25° ± 3°C and pH determined at days 2, 5, 7, 14, 28, 56, and 84. Irrigating with even moderately alkaline water over three months increased pH substantially above levels resulting from dolomite amendments alone.
Abstract
All fungicides applied as dips to polyurethane propagation cubes prior to propagation of poinsettia (Euphorbia pulcherrima Willd.) cuttings inhibited rooting at the concentrations employed. Least inhibition of rooting resulted from dips containing (per liter) either 37 mg metalaxyl [N-(2,6 dimethylphenyl)-N-(methoxyacetyl) alanine methyl ester] 25 WP plus 300 mg ferbam (ferric dimethyldithiocarbamate) 76 WP, 500 mg ferbam 76WP, or 599 mg benomyl [methyl l-(butyl-carbamoyl)-2-benzimidazole-carbamate] 50 WP. Treatments containing fenaminosulf (p-dimethylaminobenzenediazo sodium sulphonate) 35 WP inhibited rooting most. The PCNB (pentachloronitrobenzene) 75 WP treatment also caused low root counts.
The eriophyid mite, Phyllocoptes fructiphilus, vectors the causal agent, Rose rosette virus (RRV), that results in rose rosette disease. Parts of the southeastern United States have remained free of the disease, except for infected plant material introductions that were eradicated. A survey of sampling points through Alabama, Georgia, and Mississippi (n = 204) revealed the southeastern border of RRV. The presence of RRV in symptomatic plant tissue samples (n = 39) was confirmed by TaqMan-quantitative reverse transcription polymerase chain reaction (RT-qPCR). Samples were also collected at every plot for detection of eriophyid mites, specifically for P. fructiphilus. Three different species of eriophyid mites were found to be generally distributed throughout Alabama, Georgia, and Mississippi. Most of these sites (n = 60) contained P. fructiphilus, found further south than previously thought, but in low populations (<10 mites/gram of tissue) south of the RRV line of incidence. Latitude was found to be significantly correlated with the probability of detecting RRV-positive plants, but plant hardiness zones were not. Plot factors such as plant size, wind barriers, and sun exposure were found to have no effect on P. fructiphilus or the presence of RRV. The reason for the absence of RRV and low populations of P. fructiphilus in this southeast region of the United States are unclear.