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- Author or Editor: Stephen Miller* x
Abstract
Naphthalenacetic acid ethyl ester (NAA ethyl ester) applied to actively growing rootsuckers on ‘Oregon Spur Delicious’ apple trees (Malus domestica Borkh.) at 0.5 and 1.0% provided effective sucker suppression 70 days after treatment. Combination sprays of NAA and N-butyl-N-ethyl-a,a,a-trifluro-2,6-dinitro-p-toluidine (benefin) or NAA and straight chain fatty alcohols (Off-Shoot-T85) gave good control of rootsuckers. Lower rates of NAA and NAA plus Off-Shoot-T85 were equally effective when a paraffin based petroleum oil spray adjuvant (Agicide Activator) was added. NAA at 1.0% was the only treatment to provide effective rootsucker supression in the season following treatment.
Combinations of diuron, simazine, and terbacil were applied every year over 15 and 16 years to the same plots. Apple (Malu×domestica Borkh.) and peach (Prunus persica L.) trees then were planted 1 and 2 years following the last herbicide application. In general, apple-tree growth was not affected, but peach tree growth was reduced by some herbicide treatments. Peach-tree growth was reduced in plots treated with terbacil and soil organic matter was lowest in these plots. Time of last herbicide treatment did not affect apple- or peach-tree growth. The results indicated that reduced fruit-tree growth was associated with reduced soil organic matter and that residual terbacil may have inhibited peach-tree growth. Chemical names used: N′-(3,4-dichlorphenyl)-N,N-dimethylurea (diuron); 6-chloro-N,N′-diethyl-1,3,5-triazine-2,4-diamine (simazine); 5-chloro-3-(1,1-dimethylethyl)-6-methyl-2,4(1H,3H)-pyrimidinedione (terbacil).
Peach trees with a pillar (P) (columnar) or upright (UP) growth habit were planted at four in-row spacings (1.5, 2.0, 4.0, and 6.0 m) in 1999 and trained to a central leader or multiple leader system to evaluate their performance in an orchard environment. A standard (S) form peach cultivar (`Harrow Beauty') was included for comparison. In this replicated study using a split-split-split plot design, one-half of the trees were summer pruned (SP) 6 weeks before harvest in each growing season from 2001 to 2003. Growth habit, tree spacing, and SP had a significant effect on tree growth and time necessary for dormant pruning. Growth habit and spacing also affected time required to summer prune. Total pruning time for all growth habits was significantly greater for SP trees compared to non-SP trees. Cumulative yields per tree were greater for UP and S habit trees than P trees over the first four seasons. Per tree yields increased as the in-row spacing increased but were decreased slightly by SP. UP trees consistently produced larger size fruit than P or S trees. Potential yields per ha and pruning times based on projected best tree spacings will be presented. UP form trees provide a good transition for growers going from low-density to high-density peach systems, with significant advantages in yield and fruit quality.
Abstract
Pressure injection of certain plant growth regulators into pruned and unpruned apple (Malus domestica Borkh.) seedlings reduced terminal growth and increased lateral development within 7 weeks of injection. One ml of daminozide (butanedioic acid mon-(2, 2-dimethylhydrazide), AVG (aminoethoxyvinly glycine), MBR 18337 (N-(4-(ethylthio)-2-(trifluoro-methyl) phenyl (-methanesulfornamide) or PP333 [l-(4-chlorophenyl)-4, 4-dimethyl-2-(l,2,4-triazol-l-yl) pentan-3-01] reduced terminal extension growth over controls. PP333, the most effective growth inhibitor tested at 0.5 mg/ml, reduced terminal extension growth by 80% over controls. Top and root fresh weight were reduced on pruned seedlings. Only PP333 reduced top weight among the chemicals tested; root weight was not affected by chemical injections. Budbreak was increased significantly by BA (6-benzylamino purine), mepiquat-chloride (N-N-dimethyl-piperidinium-chloride) and AVG, but these chemicals had little or no effect on terminal extension growth.
Abstract
Two-year-old peach trees [Prunus persica (L.) Batsch cv. Candor] on ‘Lovell’ rootstock were summer-pruned (selective thinning and heading of current season's growth) 23 days before harvest. Pruning did not affect fruit quality. Summer pruning increased yield the subsequent year, apparently by increasing fruiting wood in the center of the tree. Summer pruning vigorous 3-year-old ‘Loring’ peach trees 8 weeks before harvest increased PAR through the canopy, 1 m above the ground, immediately after pruning and when measured at harvest. Fruit from summer-pruned ‘Loring’ were firmer, with lower soluble solids than those not summer-pruned.
Abstract
Low volume (concentrate) sprays to 7.5X (375 liters/ha) of BA applied at fixed rates (137 and 228 g/ha) with airblast equipment were as effective as full dilute applications (2800 liters/ha) for inducing branch development on young apple (Malus domestica Borkh.) trees. Sprays of BA or BA + gibberellin A4+7 (Promalin) applied in a spray solution based on tree-row-volume increased branching significantly at IX but failed to produce a response when applied as a concentrate spray at a fixed chemical rate. Cultivars responded similarly to changes in spray volume.
To control excessive growth, vigorous `Smoothee Golden Delicious', `Jonagold', `Empire', and `Gala' apple (Malus domestica Borkh.) cultivars on Malling 7A (M.7A) rootstock planted at close in-row spacing (2.5 or 1.8 m) were mechanically root-pruned (RP), trunk-scored (TS; ringing), or both, annually for 3 to 5 years beginning in the fourth leaf. Trees were grown in a deep, well-drained, fertile soil and supplied with trickle irrigation. RP reduced terminal shoot length in 2 of 5 years on `Smoothee Golden Delicious'; trunk cross-sectional area (TCSA) was not affected by RP. TS reduced terminal length in 3 years and TCSA in each of 5 years of treatment on `Smoothee Golden Delicious'. Bloom density was not affected by RP on `Smoothee Golden Delicious' but was increased by TS in two of the three years measured. RP reduced terminal shoot length in `Gala', `Empire', and `Jonagold' in most years and TCSA in 1993 for all cultivars. TS had no effect on shoot length or TCSA in these three cultivars. Effects of RP and TS on yield and fruit size varied with year and cultivar. In general, the effects of RP and TS were inconsistent and often failed to reduce shoot growth or canopy spread. No practical advantage was recognized from these techniques for young apple trees growing on a fertile site with trickle irrigation.
Abstract
Sprays of poly-l-p-methen-8-9-diyl (Vapor Gard) or di-l-p-menthene (Wilt Prüf NCF), two antitran-spirants, or emulsifiable A-C polyethylene and octyl phenoxy polyethoxy ethanol (Plyac), a latex type spray adjuvant, at 0.5, 1.0 and 2.0% applied 14 days before “normal” harvest generally increased the size of ‘Stark-rimson Delicious’ apples (Malus domestica Borkh.) over unsprayed controls under conditions of low soil moisture. Antitranspirant or spray adjuvant treatments had little or no effect on average fruit diam when applied to trees growing under adequate soil moisture. The rate of chemical application had an effect on the fruit size response. Results indicated no additional benefit in fruit size when fruit were harvested 21 days after treatment (7 days after normal harvest). Treatments generally reduced fruit firmness and hastened the loss of starch from the fruit flesh.
Abstract
Vigorous, young trees of ‘Topred Delicious’ apple (Malus domestica Borkh.) either dormant-pruned or left unpruned at the end of the previous season, were summer-pruned at 8, 12, 16, or 20 weeks after full bloom (WAFB) by thinning, heading, or stubbling current season to 2-year-old shoots. The amount of new growth following summer pruning (regrowth) was influenced by the date of pruning; late pruning (20 WAFB) generally produced less regrowth than earlier pruning (8 WAFB). Regrowth also varied with moisture conditions during 2 growing seasons. Severe heading or stubbing of vigorous vegetative shoots to 2 or 3 nodes resulted in flower bud initiation on some spurs produced from axillary buds on these stubs. The degree of fruit bud initiation was related to time of pruning and moisture supply. Summer pruning generally increased the percentage of sunburned fruit harvested, but there was no consistent effect on fruit size, color, flesh firmness, or soluble solids.
Abstract
Growth of ‘Topred Delicious’ (Malus domestica Borkh)/Malling Merton (MM) 111 apple trees during the first 5 years in the orchard was significantly affected by the orchard floor management system. Trees grown in a mowed sod were smaller and had a significantly lower yield efficiency (kg/cm2) than those grown under cultivation or a herbicide strip system. N source or rate did not influence growth or average yield/tree; fruit size and bitter pit development were significantly greater where a complete fertilizer (10N-4P-8K) was applied. N increased tree growth under sod but not under a cultivated or herbicide strip managment system. Growth response in the first year was increased when larger-sized trees were planted under a weed-free management system and trees were headed to 76 cm.