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  • Author or Editor: R. E. Byers x
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Submerging `Stayman' apples in nonionic and anionic surfactant-water solutions caused increased water uptake and fruit cracking. The primary sites of water uptake were lenticels and injured areas of the fruit cuticle. Fruit cracking caused by submerging fruit in 1.25 ml X-77/liter surfactant was used to predict the natural cracking potential of `Stayman' strains and apple cultivars in the field. Submerging apples in aqueous pesticide mixtures did not Increase fruit cracking or water uptake. Fruit cracking and uptake of surfactant-water were not correlated between apple cultivars. In a surfactant-water bath, `Starkrimson Delicious' absorbed more water than `Stayman', `York', `Jonathan', and `Golden Delicious'; no `Starkrimson Delicious' fruits cracked, but 32% to 80% of the other cultivars did. In field tests, four airblast spray applications of GA4+7 in July and Aug. 1987 reduced fruit cracking from 56% to 21%, and five applications In July, Aug., and Sept. 1988 reduced fruit cracking from 93% to 75%. In 1987, daminozide reduced cracking, but, in 1988, neither daminozide, NAA, nor Vapor Gard alone reduced cracking. However, in 1988, a combination treatment of GA4+7, daminozide, NAA, and Vapor Gard reduced fruit cracking from 93% to 22%. Also, two scorings of the trunk with a carpet knife reduced fruit cracking 22%. Chemical names used: alkylaryl polyoxyethylene alcohol glycol (X-77); butanedioic acid mono(2,2-dimethylhydrazide) (daminozide); naphthaleneacetic acid (NAA); di-1-p-methene (Vapor Gard); gibberellic acid (GA4+7).

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Abstract

Excellent control of pine voles (Microtus pinetorum) and meadow voles (M. pennsylvanicus) was achieved using several commercially formulated, pelletized anticoagulant baits as a single broadcast treatment. A new pelletized formulation of zinc phosphide (Zn3P2) was shown to kill about 30% more voles in both hand-placed and broadcast field trials when compared to one of the commercially available, surface-coated 2% Zn3P2corn and oat formulations. Hand-placed cellophane- or plastic-packaged rodenticides were shown to be effective. Packs hand-placed under 2 types of covers (cinder blocks or split tires) gave equivalent control. Since about 5% of the hand-placed packs were not opened where voles were known to be present, a low but residual population was sufficient for repopulation of the orchard.

Open Access

Abstract

Perfect flowers were induced on a gynoecious line of muskmelon with foliar applications of 5-methyl-7-chloro-4-ethoxycarbonylmethoxy-2, 1, 3-benzothiadiazole (MCEB) at the 4th leaf stage. Following hand-pollination, fruit was set, and seed developed. This method permits maintenance of gynoecious lines for the production of Fj hybrid muskmelon seed.

Open Access

Shading (92%) of `Redchief Delicious' apple (Malus domestics Borkh.) trees for 10-day periods from 10 to 20, 15 to 25, 20 to 30, and 25 to 35 days after full bloom (DAFB) caused greater fruit abscission than shading from 5 to 15, 30 to 40, 35 to 45, or 47 to 57 DAFB. Fruit 8 to 33 mm in diameter (10 to 30 DAFB) were very sensitive to 10 days of shade, even though fruit sizes of 6 to 12 mm are considered the most sensitive to chemical thinners. In a second test, shading for 3 days caused fruit thinning; 5 days of shade in the periods 18 to 23, 23 to 28, and 28 to 33 DAFB caused greater thinning than 11 to 16 or 33 to 38 DAFB. Shading reduced photosynthesis (Pn) to about one-third that of noncovered trees. Terbacil (50 mg·liter-1) + X-77 surfactant (1250 mg·liter-1) applied with a hand-pump sprayer 5, 10, or 15 DAFB greatly reduced fruit set and caused some leaf yellowing, particularly in the earliest treatments. Terbacil reduced Pn by more than 90% at 72 hours after application. Shoot growth of trees defruited by shade or terbacil was equivalent to defruited or deblossomed trees; ethephon (1500 mg·liter-1) inhibited tree growth and defruited trees. No terbacil residues were dectected in fruit at harvest from applications made 5, 15, 20, 25, or 30 DAFB. Eleven of 12 photosynthesis-inhibiting herbicides were also found to thin `Redchief Delicious' apple trees. Shading caused more thinning than terbacil at the later applications, which may reflect poorer absorption and/or lesser photosynthetic inhibition than when terbacil was applied to older leaves.

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Abstract

Greenhouse studies were conducted to identify a chemical that would temporarily suppress net photosynthesis (Pn) of peach leaves. Antitranspirants and photosynthetic inhibitors were tested on leaves of greenhouse-grown peach trees [Prunus persica (L.) Batsch]. Leaf dips of 8% Vapor Gard (poly-1-p-methen-8-9 diyl), 10−3 m ABA, 10−3 m diuron, and 10−3 m terbacil reduced Pn by more than 50% within 1 day after treatment, without causing excessive visual phytotoxicity. Since terbacil strongly reduced Pn with minimal phytotoxicity, it was applied as limb treatments to bearing ‘Madison’ peach trees in the field. Treatments were single applications at 1000 or 2000 ppm, double applications a week apart at 1000 ppm, or 2000 ppm at week 1 followed by 1000 ppm at week 2. Fruit drop was 73% to 90% on terbacil-treated limbs compared to 20% natural drop on nonthinned controls. All terbacil treatments increased the size of remaining fruit over that of the nonthinned checks. The 1000 ppm treatment resulted in fruit size similar to the hand-thinned check, but higher concentrations caused smaller fruit than the hand-thinned control.

Chemical names used: abscisic acid (ABA); N’-(3,4-dichlorophenyl)-N,N-dimethylurea (diuron); 5-chloro-3-(1,1-dimethylethyl)-6-methyl-2,4(1H,3H)-pyrimidinedione (terbacil).

Open Access

Abstract

Chemicals deposited on foliage varied by a factor of three to five times when sprays were applied with an airblast sprayer to apple (Malus domestica Borkh.) trees in various training systems. Deposits were higher with vertical than horizontal training systems, smaller tree sizes, and less-dense tree canopies of spur-type trees. The Lincoln canopy tree training system prevented good spray penetration because the airblast spray pattern was split by the horizontal nature of the canopy.

Open Access

Abstract

Foliar copper deposits varied by a factor of 5-fold when copper was applied with an airblast sprayer at a rate of 935 liters/ha (100 gallons/acre) to trees of apple (Malus domestica Borkh.). Higher deposits were recorded as tree size decreased. Chemical deposit was related inversely to percentage of light penetration through the canopy.

Open Access

Abstract

Shading of nectarine [Prunus persica (L.) Batsch] scaffold limbs 45-58 days after full bloom caused seed discoloration and fruit abscission. Shading of peach [Prunus persica (L.) Batsch] scaffold limbs from 31-41 days after full bloom caused greater fruit adscisson than shading from 11-21 or 21-31 days after bloom. The photosynthetic inhibitor, 3-tert-butyl-5-chloro-6-methyluracil (terbacil), applied to whole trees 35 days after full bloom induced fruit abscission. Terbacil at 500 ppm or higher caused excessive thinning. Fruit size was larger than hand thinned fruit, since overthinning occurred. Fruit color, soluble solids, and firmness of fruit from the 500 ppm treated trees were similar to fruit from hand thinned trees. No leaves abscissed, but marginal chlorosis occurred on less than 30% of the leaves at harvest. Flower bud numbers per cm of terminal length were similar to the hand thinned trees, but much greater than unthinned trees. Residue analysis of fruit at harvest from the 500 ppm terbacil treatment revealed 0.07 ppm in the fruit.

Open Access

Effects of Tergitol-TMN-6 surfactant on blossom thinning (fruit set), fruit quality, and yield were studied in different cultivars of peach (Prunus persica [L.] Batsch) during 2003 to 2005, and in one cultivar of nectarine Prunus persica [L.] in one orchard and one cultivar of plum (Prunus domestica [L.]) in two orchards in 2004. In addition to Tergitol-TMN-6, effects of Crocker's fish oil (CFO) alone in three peach cultivars or in combination with lime sulfur in a nectarine cultivar were studied on fruit set, quality, and yield. Tergitol-TMN-6 at 5 mL·L–1 or higher rates, applied at about 75% to 85% bloom, reduced fruit set without russeting peach fruit. Peach fruit size was often increased by Tergitol-TMN-6 treatment. Applications of Tergitol at 20 mL·L–1 or 30 mL·L–1 excessively thinned peaches. Tergitol-TMN-6 at all rates burned foliage, but the symptoms disappeared after a few weeks without any adverse effects on tree productivity. Tergitol-TMN-6 at 7.5 mL·L–1 or 10 mL·L–1, applied either once at about 80% to 85% bloom or twice at 35% bloom and again at 80% to 85% bloom, reduced fruit set without any fruit russeting in nectarine. Tergitol-TMN-6 at 7.5 mL·L–1 to 12.5 mL·L–1 reduced fruit set in `Empress' plum. CFO at 30 mL·L–1 was effective in blossom thinning of some peach cultivars. A combination of lime sulfur and CFO was not effective in blossom thinning of nectarine. Considering results from several orchards in different locations in the Pacific Northwest over 3 years, Tergitol-TMN-6 is an excellent blossom thinner for peach, nectarine, and plum at rates of 7.5 to 12.5 mL·L–1, sprayed at a spray volume of 1870.8 L·ha–1 when about 75% to 85% blooms are open.

Free access