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  • Author or Editor: R. E. Byers x
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`Fuji'/MM.111, `Pink Lady'/M.7A, and `Summerfield'/M.7A apple trees were planted in several types of individual root restrictive bags in the field in 1995. Bags were made of Knit and Woven fabrics, Galvanize hardware cloth (6.4 cm) with various holes sizes and of different bag volumes. The bags confined the development of large roots to within the bag. Roots that penetrated the bag resulted in root branching and large root inhibition. As the roots enlarged, roots penetrating the bags were restricted in diameter by the fabric hole size. Roots enlarged to some degree on both sides of the fabric holes but were not killed by girdling within the first few years. Root restriction bags decreased trunk caliper, shoot growth, pruning weights, number of cuts per tree, increased flowering, fruit numbers, and weight per tree. Fruit firmness, soluble solids and color was increased and starch was lower than the nonbagged controls. In cage and tank trials pine and/or meadow voles easily penetrated all of the fabric and polypropylene bags within 24 h, except for the galvanized hardware cloth (6.4 cm). Susceptibility of each material to vole damage was tested by placement of an apple inside a small bag of each. Root restriction bags seemed to be a viable alternative to dwarfing rootstocks for control of tree size, early flowering, and early fruiting.

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Prohexadione calcium applied as a series of three applications starting soon after petal fall to `Fuji'/M.9 apple trees reduced the number of pruning cuts, pruning time, pruning weight per tree, current season's shoot length, individual shoot weights, and increased number of nodes on the lower 40 cm of shoots. Fruit diameter, soluble solids, starch, or individual fruit weights were not affected by Apogee sprays. Fruit color and firmness were slightly increased in only one experiment. Growth suppression appeared to be greater on trees cropping more heavily. When trees were more heavily thinned, less shoot growth control was achieved. Apogee applied at 250 mg/L in three applications caused a significant increase in fruit set when compared to the control. Alone Vydate, Carbaryl+Oil, or Carbary+Accel+Oil caused fruit thinning, but neither ethephon nor shading 3 days caused significant thinning. Apogee did not influence results of chemical thinners when applied between the first and second Apogee applications. The 10% and the 27.5% Apogee formulations gave similar shoot growth inhibition when applied with Regulaid or Oil+Silwet L-77. When using hard water (well water), the 27.5% Apogee formulation was not as effective as the 10% formulation. The 10% Apogee formulation has more NH4SO4 than the 27.5% formulation w/w; NH4SO4 is used to prevent inactivation of Apogee by calcium and other cations when hard water is used for spraying. The addition of CaCl (frequently used to reduce bitter pit and corkspot disorders) to the 27.5% Apogee formulation caused poorer growth control than with hard water alone. When Apogee was used at 125 mg/L, the addition of NH4SO4 restored the effectiveness of the hard water+CaCl mixture. Alone the additives NH4SO4, Ca Cl, Regulaid, and/or Oil plus L-77, had no effect on tree growth. Apogee plus L-77+Oil provided additional growth suppression when compared to Apogee+Regulaid. In 1998, three applications of Apogee (63 mg/L) or ethephon (135 mg/L) did not affected shoot growth of `Fuji'/M.9 trees at these low rates. Combinations of Apogee and ethephon gave good control of tree growth. Flowering and fruit set were not promoted by any of these applications.

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Effectiveness of pollination/fertilization inhibitors for flower thinning depends highly on the precise timing of sprays within 24 to 36 h after flower opening. In 1999, cool weather delayed the application of hormone-type thinners, which were intended for at bloom comparison with pollination/fertilization. Pollination inhibitors applied in bloom and hormone thinners applied at petal fall or 8 mm fruit diameter caused good fruit thinning. Ethephon applied in bloom did not cause thinning of `Empire' fruit, but Sevin + Accel + Oil caused good fruit thinning when applied in bloom. Sevin + Accel + Oil increase fruit diameter and did not affect fruit russet. Ethephon applied at 22 mm fruit diameter at water rates of 935 L/ha or 3741 L/ha and chemical rates of 21.5 L/ha or 42.9 L/ha did not cause significant fruit thinning. In 1998, pollination inhibitors and hormone-type growth regulators caused flower and fruit thinning of `Starkrimson'/MM111/106 trees. Good thinning occurred with both pollination inhibitors and ethephon treatments; but Sevin + Accel + oil was not as effective. Thinex caused the most side russet. Treatments that thinned generally caused increased fruit diameter. In 1999, return bloom was promoted by early thinning, but ethephon did not appear to promote return bloom beyond the thinning effect. In 1998, endothall caused good thinning of `York'/MM.111 with a minimum of foliage injury. Fruit diameter was increased. Thinning with endothall in 1998 greatly increased return bloom in 1999, but trees were slightly over thinned. Fruit injury caused by carbaryl was almost non-existant in 1999 in two tests having over 25 carbaryl treatments that compared different formulations and adjuvants for thinning and injury. Some very slight, non-significant injury, may have occurred with three of nine formulations tested when trees were shaded. Shading trees for 1 day in conjunction with carbaryl sprays also did not promote injury. In a previous year, shading trees promoted carbaryl injury. A tank mix of Oil with either 50WP, 80WP, XLR, or 4L formulations caused 3 to 8% of the fruit to show injury at a very low intensity. However, in an adjoining block, Sevin + Accel + Regulaid caused injury to >50% of the fruit when applied the same day as the other experiments. Further investigations on this problem are in progress.

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Heavily cropping `York'/M.27 trees sprayed with seven multiple low doses of ethephon (135 mg/L each) did not cause greater return bloom in 1999 unless foliar fertilizers (either 18–18–18 or Ca N03) were added to the ethephon sprays. Foliar fertilizer sprays alone did not promote return bloom. `York'/M.7 trees selected for very little bloom in 1997 (“off year” of the biennial bearing cycle) and sprayed with 160 mg/L GA3 or 320 mg/L GA3 had significantly less return bloom in the 1998 (“on year”) (61% and 46% spurs flowering, respectively, compared to control trees that had 99% of spurs flowering). Trees sprayed in 1997 (“off year”) with GA3 return bloom and cropped in 1999; but trees in the “off year” in 1997 that were not sprayed with GA3, did not crop in 1999. Sprays of GA3 provided some control of alternate bearing of `York'/M.7 trees when applied in the “off year” of the biennial bearing cycle. Leaves taken from `Braeburn'/M.27 trees in 70 °F rooms evolved ethylene through out the 12 days of the test. A moderate ethylene peak occurred on about days 5 and 6. Leaves from trees in the 40 °F room did not evolve detectable ethylene levels until trees were put in another 70 °F room on day 6. Ethylene levels were about the same from day 6 through day 12 for all treated trees at 70 °F. Nontreated control trees in rooms at 40 or 70 °F did not produce detectable ethylene levels during the experiment (except for a very small amount detected only on day 2 from leaves seal for 24 h at 70 °F.

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Abstract

High-budded trees of nectarine [Prunus persica (L.) Batsch] that were mechanically planted with the bud union as a depth guide resulted in poorer growth when compared to those planted with the crown roots within 5 cm of the surface. Deeper-planted trees had smaller leaves and less total increase in trunk cross-sectional area, and were more susceptible to the formation of air pockets around their bases.

Open Access

Abstract

Shallow-planted trees of ‘Delicious’ apple (Malus domestica Borkh.) on Mailing (M) 7A and Mailing Merton (MM) 111 rootstock had increased frequency of burr-knots and were less likely to be loosened in the soil by wind than were deep-planted trees. Deep-planted trees on seedling roots were more likely to be loosened by handshaking; however, burrknots were not a problem. Leaf size was larger significantly for all shallow-planted trees. Growth differences were related to soil type, rootstock, and planting depth.

Open Access

Abstract

Airblast spray applications of ammonium thiosulfate (ATS) were made to individual peach trees in a single row or to small blocks 5 rows wide and 10 trees long to determine if drift from adjacent rows increased bloom thinning. Increased flower thinning was found in the center row of the 5-row-wide-block when compared by regression analysis to applications made to trees in a single row. Ethylene-bisdithio-carbamate (Zineb 78WP) was used to determine the amount of spray deposit contributed by airblast sprays to adjacent rows. Airblast spraying of peach trees in full bloom contributed chemical deposits to peach flowers in the adjacent row equal to 43% of that deposited on the sprayed row, and 26% to the second row removed.

Open Access

Abstract

A laboratory tank test was devised to evaluate susceptibility of 1-year-old stems of 111 Malus cultivars and hybrids to damage from pine voles (Microtus pinetorum Le Conte). This method allowed several clones to be tested at one time; provided the animals with a semi-natural environment in the laboratory; exposed each animal to all stems in the test; and required only small quantities of wood per clone. Cultivars displaying a high degree of resistance to pine vole gnawing included: Malus fusca (Raf.) Schneid. H15; M. sieboldii (Reg.) Rehd. zumi calocarpa; M. × sublobata (Zab.) Rehd. PI 286613; NY 11928 (M. pumila niedzwetzkiana (Dieck) Schneid. × M. × atrosanguinea (Spaeth) Schneid.); M. × robusta (Carr.) Rehd. No. 5 (R5); and M. yunnanensis (Franch.) Schneid. ‘Vilmorin’. Families from R5 and PI 286613 crossed with M. pumila Mill, cultivars exhibited varying degrees of vole resistance.

Open Access

Technical grade prohexadione-calcium (93.2% a.i. P-Ca) applied to `Fuji'/M.9 trees in three applications in deionized water reduced shoot growth by 25%, but the addition of (NH4)2SO4 to P-Ca suppressed shoot growth by 47%. If P-Ca was mixed in well water (high in calcium salts), P-Ca did not suppress shoot growth at all. The commercially formulated prohexadione-calcium [Apogee: 27.5% P-Ca + 56.1% (NH4)2SO4 + 16.4% other proprietary additives] + Regulaid in well water (high calcium) was not as effective (reduced growth by 30%) as when additional (NH4)2SO4 was added (reduced growth by 53%), and if CaCl2 (used to control corking) was tank mixed with Apogee + Regulaid, the Ca++ interfered with the growth suppression of P-Ca. If (NH4)2SO4 was added at the same rate as CaCl2 (w/w), the Apogee growth suppression was completely restored (reduced growth by 50%). Choice (a commercial water conditioner that has (NH4)2SO4 in the formulation, among other ingredients) + Li-700, or (NH4)2SO4 + Silwet L-77, or (NH4)2SO4 + Silwet L-77 + Oil were among the most effective adjuvant combinations with Apogee. The addition of ethephon at 270 mg·L-1 improved the growth suppression of Apogee + (NH4)2SO4 + Regulaid. Solubor compromised the effectiveness of Apogee + Regulaid. Adjusting the pH of the Apogee + (NH4)2SO4+ Regulaid spray to either pH = 4 or pH = 9 did not affect efficacy. The combination of Apogee + (NH4)2SO4 + Regulaid caused increased fruit cracking of `Empire' fruit as compared to the control (7%), presumably due to increased absorption of P-Ca. Chemical names used: Prohexadione-calcium (P-Ca, 3-oxido-4-propionyl-5-oxo-3cyclohexenecarboxylate) formulated as BAS-125 (10% P-Ca); Apogee (27.5% P-Ca), or Technical 93.5% P-Ca); Regulaid (polyoxyethylenepolypropoxy-propanol, alkyl 2-ethoxethanol, and dihydroxy propane); Silwet L-77 (polyalkyleneoxide modified heptametyltrisiloxane, silicon surfactant), LI-700 (80%, phosphatidylcholine, methylacetic acid and alkyl polyoxyethylene ether); Superior Oil (Drexel Damoil 70-second delayed dormant spray oil); ethephon (2-chloroethyl phosphonic acid); Solubor (20.5%, Boron equivalent); captan (N-Trichloromethylthio-4-cyclohenene-1,2-dicarboximide).

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Terbacil applied to whole-spur `Delicious' apple (Malus domestica Borkh.) trees reduced photosynthesis and fruit set. The addition of the surfactant X-77 to terbacil sprays increased fruit thinning and leaf injury. Terbacil sprays applied to leaves only (fruit covered with foil) were as effective as when applied to leaves plus fruit. Dipping fruit alone in a terbacil solution did not cause abscission. Shading trees for 4 days with 92% polypropylene shade material reduced fruit set =50%. Spraying trees with carbaryl reduced fruit set by 25%. The combination of shade + carbaryl spraying reduced fruit set by 89%. Chemical names used: l-naphthalenyl methylcarbamate (carbaryl); 3-tert- butyl-5-chloro-6-methyluracil (terbacil); 2-chloroethylphosphonic acid (ethephon); alkaryl polyoxyethylene alcohols (X-77).

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