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- Author or Editor: W. E. Roberson x
Plants of Rosa `Mr. Lincoln' and `Peace' were established in March 1992. Using a RCB design, fungicide treatments were initiated on 15 May and terminated on 22 Oct. 1992. Foliar applications were made with a Birchmeier® Closed System Unit equipped with a ConeJet® #5500 adjustable spray tip at 50-65 psi. Treatments were cyproconazole at 0.1, 0.2, and 0.4 kg·ha-1 applied at either 14 or 28 day intervals, mancozeb at 2.250 g·1-1 applied every 7 days, and an untreated control. Cyproconazole treatments were applied in 946 1·ha-1 water and mancozeb was sprayed to runoff. Disease pressure and plant defoliation ratings were taken on 29 June and 26 August. The disease rating was based on a scale of 1-10, where 1 = no infection and 10 = severe infection and defoliation. The defoliation rating was based on a scale of 1=10, where 1=0-10% and 10=91-100% defoliation of canopy. A full season control rating was determined on 17 Nov. 1992, based on a scale of 1-3, where 1=excellent, 2=acceptable, and 3=unacceptable control of blackspot. Blackspot control with mancozeb was unacceptable on either cultivar. Cyproconazole at 0.1 kg·ha-1 every 28 days did not control blackspot by mid-November with `Peace' and was marginally acceptable on `Mr. Lincoln'. Season long disease control was near excellent for both cultivars with 0.2 kg·ha-1 cyproconazole every 28 days. All other cyproconazole treatments proved to be excellent.
Plants of Rosa L. `Peace' were field planted in Feb. 1995 in order to test black spot (Diplocarpon rosae Wolf) control efficacy of several compounds. Plants were protected from fungal infection by black spot with weekly sprays of chlorothalonil (Daconil) from 5 Apr. to 8 June 1995 to allow plant establishment. Spray treatments for efficacy testing were started on 23 June and ended on 1 Nov. 1995. All plants were uniformly weeded, fertilized, and irrigated as needed for the duration of the experiment. Plants were rated for defoliation and disease development on 18 July, 1 Sept., and 10 Nov. 1995. A wettable granular formulation of cyproconazole (Sentinel) controlled black spot significantly better when a surfactant, Latron B-1956, was added to the spray solution at 0.5 mL·L–1. Differences between treatments with and without surfactant were greater at lower rates vs. higher rates of cyproconazole. The most effective Sentinel rates with the surfactant were 0.13 g·L–1 applied every 14 days or 0.26 g·L–1 every 21 days. A formulated combination of chlorothalonil and thiophanate methyl (ConSyst) controlled black spot on a 7-day interval at 1.2 g·L–1, but not when applied at 1.8 g·L–1 every 14 days. Control was no better than the standard mancozeb (Dithane) treatment. Neem oil (NeemGard) was not effective on the 14-day schedule tested. Tank mixing neem oil with chlorothalonil or thiophanate methyl (Domain) did not significantly improve control. Neither myclobutanil (Systane) or a formulated combination of mancozeb and myclobutanil (RH 0611) was effective in controlling black spot.
Viola tricolor seed were exposed to aerated solutions of water or 300 or 400 mM NaCl for 0, 2, 4, 6, or 8 days. After priming treatments, seed were air dried, placed on moist filter paper in petri dishes, and set in dark growth chambers at 18 or 30°C for germination. priming for 6 days in water increased germination of `Crystal Bowl Yellow' seed from 80 to 88% when germinated at 30 °. Untreated seed germination was 92% at 18°. Priming for 6 days in 300 mM NaCl improved germination of `Majestic Giant Blue' seed from 57 to 76% when germinated at 30°. Untreated seed germination was 80% at 18°. These data indicate that seed priming could be used to improve summer germination of a cool season annual. Priming increased germination at the higher than optimum temperature (30°) to levels similar to that for the optimum temperature (18°). However, the best priming solution depended on the cultivar.
Consistent sprout control was obtained with peach trees (Prunus persica (L.) Batsch cv. Sungold) when 0.25, 0.5, 0.75 or 1% naphthaleneacetic acid (NAA) was applied to pruning cuts during 2 years with sprout control generally proportionate to concentration. NAA treatments induced gummosis around the pruning cuts with the degree of gummosis related to concentration.