Container grown `Shishi-Gashira' camellias received a single foliar spray of 0, 5, 10, 15, 20, 40, or 60 mg a.i. liter uniconazole on 26 May 1989. Growth indices were determined about every 4 weeks during the 1989 growing season and following the spring 1990 growth flush. Flowering was also monitored. Growth was suppressed linearly or quadratically over the duration of the test, with growth inhibition 12 months after treatment ranging-l from 3.7% (5 mg a.i. liter-1) to 20.6% (60 mg a.i. liter-1) relative to the control Flower number increased from 52.6% (5 mg a.i. liter-1) to 100% (60 mg a.i. liter-1) compared to the control. Time to flower was not affected by 5 to 20 mg a.i. liter-1 uniconazol but increased 4 to 7 days with the 40 and 60 mg a.i. liter-1 rates. Uniconazole rate did not affect flower diameter.
Own-rooted, 4-year-old kiwifruit plants [Actinidia deliciosa (A. Chev.) C.F. Liang et R. Ferguson var. deliciosa] protected by a Styrofoam insulation wrap with a water-filled pouch (Reese clip-on trunk wrap) or by microsprinkler irrigation sustained less freeze injury than unprotected plants under field conditions at temperatures as low as -17.8C. Trunk splitting occurred on the plants, but no injury was detected on canes, buds, or shoots in the canopy of the plants. Unprotected plants had more trunk splitting and at greater heights than protected plants. New canes developed from suck- ers of cold-injured plants and developed a trellised canopy the following season.
Adequate fruit thinning of ‘Loring’ peach [Prunus persia (L.) Batsch] was achieved with single applications of (2-chloroethyl)-methylbis (phenylmethoxy) silane (CGA 15281) at concentrations of 240, 360, and 480 ppm applied at seed length of 8.8 mm and 2 applications at 240 and 360 ppm applied 7 days apart at 8.8 and 10.8 mm seed lengths in 1978. Additional hand thinning following treatment was required. In 1979 adequate thinning was achieved with 1 application of 240 ppm applied at seed length of 13.9 mm or 480 ppm applied at an 8.5-mm seed length. Yields from these treatments were reduced but did not differ from the control treatment. Multiple applications and higher rates resulted in over-thinning and reduced yields. The sensitivity of fruit to thinning appeared to increase with increased seed length. In 1978, foliage injury occurred at all rates and the severity of injury increased at higher concentrations and multiple applications. However, no foliage injury was observed in 1979.
The postemergence-active herbicides lactofen, fomesafen, and acifluorfen were applied to established matted-row strawberry plants (Fragaria × ananassa) and evaluated for broadleaf weed control and foliar phytotoxicity. Strawberries were evaluated for yield and fruit quality. Treatments were applied following June renovation. All herbicide treatments resulted in acceptable control of broadleaf weeds present at the time of application; however, sicklepod (Cassia obtusifolia) germinated after herbicide application. All treatments caused foliar injury within 3 days after application. No injury symptoms were evident 21 days after treatment due to new foliage development. Fomesafen and acifluorfen were the only herbicides to suppress runner count. Yields the following year were not reduced by herbicide treatments. Chemical names used: (±)-2-ethoxy-l-methy1-2-oxoethyl 5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrobenzate (lactofen); 5-[2-chloro-4-(trifluoromethyl)phenoxy] -N -(methylsu1fonyl)-2-nitrobenzamide (fomesafen); 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid (acifluorfen).
Hydrogen cyanamide (Dormex) treatments were applied to 17 insufficiently chilled peach and nectarine cultivars ≈6 weeks after normal budbreak. Treatment effectively induced vegetative budbreak and reduced shoot dieback. The responses to Dormex treatments were linear, with the 2% rate being more effective than the 0 and 1% rates in most cases.
Three rootstock—Elberta seedling (Elb), Lovell seedling (Lov), and Vila Fria seedling (VF)—were evaluated on an old peach-orchard site to determine their susceptibility to nematodes and their effect on growth, yield, survival, and foliar nutrient content of ‘Loring’ peach [Prunus persica (L.) Batsch]. During the first 6 years of the orchard's life, mortality rates of the trees were 18% (Elb), 21% (Lov), and 47% (VF). Rootstock did not affect tree height, spread, trunk circumference, or yield the first 3 crop years. However, Lov produced higher yields the 4th crop year and had a greater cumulative yield for the first 4 crop years than Elb or VF. When tree loss was taken into account, tree yield per hectare did not differ with Lov and Elb but was lower with VF. Rootstock did not affect nutrient level in the foliage. Nematode populations were low in the orchard and were unaffected by rootstock. Tree loss, yield differences, and cropping efficiency of trees on the different rootstock could not be accounted for by foliar nutrient levels, nematode populations, tree vigor, or size.
The yellow passionfruit (Passiflora edulis f flavicarpa Degener), a perennial vine grown in the tropics and subtropics, was successfully grown as an annual crop in a temperate zone. Fruit maturity was hastened by ethephon treatments to allow harvest before the mean date of the first killing frost. Maturity was advanced in a linear manner with application rates of 150, 300, and 600 ppm ethephon. Total yield was not affected by ethephon treatment; however, cull fruit producing no juice increased with increasing rates of ethephon, thereby reducing marketable yields. Soluble solids and ascorbic acid contents of the juice were not affected by ethephon treatment. Purple passionfruit (Passiflora edulis Sims) did not produce blossoms.
Field studies were conducted over three seasons to determine the effect of N and K on susceptibility of tomato to bacterial spot. A factorial randomized complete block design consisting of four rates of N (167, 334, 501, and 668 kg·ha–1) and three rates of K (334, 668, and 1335 kg·ha–1) were used. Liquid fertilizer was injected via trickle irrigation. Increasing N rates reduced disease severity, whereas the effect of increasing K was inconsistent from season to season. The concentration of N in leaf tissue showed a significant negative correlation with disease severity, whereas the concentration of Ca in leaf tissue exhibited significant positive correlation with disease severity and negative correlation with N rate during two seasons of data collection.
Foliar and dormant shoot nutrient content and tree survival of ‘Loring’ and ‘Redhaven’ peach [Prunus persica (L.) Batsch] on 8 seedling rootstocks (Lovell, Halford, Harrow W-208, NA8, Nemagard, Siberian C, NC NRL-4, and NC 152-AI-2) were determined during 2 seasons. Foliar Ca levels of both ‘Loring’ and ‘Redhaven’ peach trees were lower on Siberian C rootstock than on any other rootstock in the study. Dormant stem Ca levels were lower when cultivars were on Siberian C rootstock than when on most other rootstocks. Cultivars on Siberian C had lower foliar K levels than most other scion/rootstock combinations. Some differences in foliar and stem N, P, Mg, and Mn levels were evident; however, these differences generally were small and inconsistent. After 6 years in the orchard, greatest tree loss occurred with ‘Loring’ on Siberian C and ‘Redhaven’ on Siberian C or NA-8. Other rootstocks did not affect tree survival of either cultivar. Tree width was smallest with Siberian C rootstock, but few differences in trunk circumference and tree height were observed.