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Alternate bearing in pistachio (Pistacia vera L.) is correlated with crop load; a heavy crop on l-year-old wood appears to cause abscission of inflorescence buds on current wood. Defruiting heavily bearing trees before or during the period of nut growth stopped inflorescence bud loss. This relationship between crop and bud loss was affected by the fruiting status of neighboring shoots. Large defruited branches (> 5.5cm diameter). in fruiting trees had bud retention values (50% to 65%) equivalent to fully defruited control trees, but smaller branches showed reduced bud retention levels. Bud retention was increased 2- to 6-fold in small branches when neighboring branches were defruited. Nitrogen concentration of leaves in late August was positively correlated with the final bud retention percentage and inversely correlated with defruiting date.

Abstract

The pistachio (Pistacia vera L.), characteristically a biennial bearer, produces its most extensive shoot growth in years of heavy crop production. Whereas levels of total sugars in bark and wood of bearing and nonbearing branches were similar throughout the year, starch levels tended generally to be higher in nonbearing than in bearing branches. Consequently, nonbearing branches one year gave rise to heavy crops the next and, beacuse of greater quantities of reserve foods, also produced extensive shoot growth. Bearing branches of that same year, .however, produced few or no nuts the next and, because of lesser quantities of reserve foods, produced markedly less shoot growth. No relationship between total nitrogen level and shoot growth or fruiting was evident.

Three node stem cuttings of Chrysanthemum `Fortune' were sprayed with Atrinal, 500, 1000, 1500 and 2000 ppm, to incipient runoff under greenhouse conditions. The results demonstrated that with higher levels of Atrinal, branch number, branch length, plant height, and flower number decreased in both unpinched and pinched plants. At the same time, the dry weight of both pinched and unpinched plants increased. Applications of Atrinal, 1000, 1500, and 2000 ppm, lengthened the number of days to flower by 40 days.

Abstract

Ninety-one percent to 95% of field-grown 3-year-old root systems of Gleditsia triacanthos L., Populus × generosa A. Henry, and Fraxinus pennsylvanica Marsh were outside of the harvestable root ball. Seventy-seven percent of the Populus root system was growing beyond the branch dripline, whereas 59% and 54% were outside of the Gleditsia and Fraxinus driplines, respectively. Root spread to branch spread ratios are discussed.

Abstract

Winter injury to branches of highbush blueberries (Vaccinium australe Small cv. Jersey) resulted when mechanical harvester use caused lesions on the branches during the harvesting process. Of the dead wood collected during 2 years study, more than 99% had such a lesion. The amount of wood lost increased as the vibration rates of the harvester increased and at high rates loss of bearing surface reduced production the following season.

The structure of 1-year-old trunks resulting from sylleptic branching are compared among apple (Malus domestica Borkh) cultivars with diverse branching and fruiting habits. The 1-year-old trunks developing from a graft are described as a succession of metamers whose structure refers to location, distribution, and length of sylleptic axillary shoots. We used a stochastic process called hidden semi-Markov chain to capture the embedded structure resulting from mixing of different types of axillary shoots developing along the trunks. The models, corresponding to the different cultivars, are composed of a first transient nonbranched state, a succession of transient states that cover the median sylleptic branching zone, and a final absorbing nonbranched state. They are interpreted with regard to complexity, extent, and branching distribution of the median sylleptic zone. Main results deal with the balance between long and short sylleptic shoots and the distribution of long sylleptic shoots along the trunks. Results suggest that sylleptic branching could be used as an early characteristic to evaluate the later branching behavior of cultivars.

Eighteen New Guinea impatiens cultivars were evaluated for performance as bedding plants and for suitability as hanging basket plants. The cultivars were treated with three growth retarding chemicals (B-9, Sumagic and Cutless) to determine their effect on plant growth, branching and overall flower development. Two applications of 2500 ppm B-9 produced the most commercially acceptable plants. Height and spread were reduced by approximately 30 percent with no reduction in the number of flowers produced or the number of days to bloom. Cutless and Sumagic applications reduced growth approximately 50 percent and delayed blooming as much as 2 weeks when compared to the untreated control. Growth regulator treatment had no effect on the number of branches produced except with Sumagic which resulted in an overall reduction in branching.

The inheritance of two new induced mutations for spindly branch was investigated in common bean (Phaseolus vulgaris L.). Each mutant was found to be controlled by a recessive gene. Allelism tests were performed beween a previously reported spindly branch mutant (sb) and the two new spindly branch mutants; the new mutants were found to be nonallelic to sb and to each other. The gene symbols sb-2 and sb-3 are proposed for the new mutants. Repulsion phase F₂ linkage tests were made for all nine combinations of reclining foliage (rf) and sb among the two mimic mutant series rf, rf-2, rf-3 and sb, sb-2, sb-3. No linkages were detected.

Three node stem cuttings of Algerian Ivy Hedera canariensis were sprayed with growth regulators to incipient runoff under greenhouse conditions. The results demonstrated that the combination of BA + GA₄₊₇, (Promalin) promoted branching of Algerian Ivy better than applications of BA or GA₄₊₇ alone. Plants treated with Atrinal developed more shoots per node than those treated with GA₄₊₇, BA, or Promalin. Increasing concentration of Atrinal from 0 to 3000 ppm, also reduced branch length and leaf number for both pinched and unpinched plants. 2,3,5—triodobenzoic acid (TIBA) significantly increased the branching of Algerian Ivy, although plant shape was not commercially acceptable due to epinasity of the foliage.

Four rates of seven plant growth regulators were foliar-applied to 11.4 liter containers of Photinia × fraseri after initial root establishment. Growth regulators studied were uniconazole, paclobutrazol, dikegulac-sodium, ancymidol, 6-BA, GA₄₊₇ and, 6-BA + GA₄₊₇. Six months after application, plant height, plant width, growth index, and number of lateral and terminal branches were recorded.

Applications of uniconazole (30 mg a.i./liter), 6-BA alone or in combination with GA₄₊₇, and dikegulacsodium stimulated lateral branching. The number of lateral branches increased linearly as paclobutrazol rates increased from 60 to 180 mg a.i./liter. Growth index decreased with increasing application rates of uniconazole and paclobutrazol, while the growth index of photinia treated with other growth regulators wasn't affected by application rate. Plant height was increased in GA₄₊₇ treated plants.