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The effect of soil preplant strategies winter solarization and methyl bromide fumigation were compared to a non-treated control on apple tree growth. Treatments were applied in the fall after removal of an existing orchard with spring planting of 'Jonee' and 'Smoothee Golden Delicious' on M.26 EMLA rootstock. Soil fumigation significantly increased shoot length in first year, trunk cross-sectional area increase during two seasons, and bloom and set in second year. The control and winter solarization treatments were similar in all responses. Foliar Mn concentrations were significantly lower with fumigated trees in second years compared to other two treatments, which were similar.
Summer pruning effects on apple tree canopy microclimate, fruit quality, and summer disease were studied in a commercial orchard in eastern Arkansas. Eighteen lo-year-old trees of `Golde n Delicious'/M111 were treated as follows: 1) non-pruned control, 2) moderate pruned, thinning cuts in the canopy, and 3) heavy pruned, thinning cuts in the canopy and heading shoots on the canopy periphery. Treatments were applied on 23-June, 1992. All trees were dormant pruned. PPFD and relative evaporation (RE), measured with Livingston atmometers, were measured at time of treatment, on 15-July, and at Harvest, 9-Sept. PPFD and RE were immediately increased by summer pruning but by harvest had returned to levels near the non-pruned control. Fruit firmness, titratable acidity, starch, and color were not significantly affected while soluble solids were inconsistently affected. Weight was decreased insignificantly by moderate pruning and decreased slightly by heavy pruning. Summer fruit rot incidence was similar among all treatments. PPFD and RE were significantly higher in upper positions of the canopy as compared to lower positions.
Several trials were conducted to compare standard and potential peach rootstocks. The NC-140 trial, with 'Redhaven' as the scion, included 'Halford', 'Siberian-C', 'Bailey', 'GF-677', 'GF-655.2', 'Damas', 'Citation', 'Lovell' and 'GF-43' rootstocks. All trees with 'Citation' as the rootstock died in the first three years. while 'CF-43' and 'Siberian-C' had low survivability and productivity. 'Damas' and 'GF-43' suckered profusely. 'Lovell' trees bloomed an average of one-to-three days later than all other entries. 'Halford'. 'GF-677', 'Bailey' and 'Lovell' had the highest yields. A trial comparing 'Loring' own-root and on 'Tennessee Natural' resulted in similar yields among stocks, but larger fruit and tree size with the own-root trees. 'Redskin' own-root and on 'Lovell' also resulted in similar yields among stocks, and larger tree and fruit size with own-root trees. A trial using the processing peach selection A-219 as the scion on `S-37' 'Chum Li Tao', AR-78118, 'Yarbrough Cling' and 'Lovell' resulted in highest yields and yield efficiency with 'Yarbrough Cling', 'Lovell' and 'S-37' rootstocks.
Six fertilizer regimes applied to newly planted `Smoothee Golden Delicious' and `Jonee' on M.26 EMLA were evaluated during two years of establishment. Treatments were: 1) control (no fertilizer applied), 2) spring top-dress (granular), 3) fall top-dress (granular), 4) split top-dress (granular) spring 50%/fall 50%, 5) spring fertigation, and 6) fall furtigation. All fertilizer treatments received 10g P/tree each season with triple super phosphate used for top-dress form and ammonium polyphosphate with fertigation. Ammonium nitrate was the N source for all treatments applied at a rate of 50g N/tree/year of tree age and adjusted accordingly for trees fertigated with APP. In the second year, `Jonee'-control trees had significantly more bloom than other treatments; with `Smoothee'-spring fertigated trees having more bloom than other treatments. Set, in second year however, was greater for both cultivars with spring fertigation. Trunk cross sectional area of both cultivars at the end of two seasons was significantly smaller under spring fertigation. Both fertigation treatments significantly decreased soil pH over two seasons with an associated increase in foliar Mn occurring.
Pesticides and alternative fruit thinners are needed for certified organic fruit growers. Transient reductions in photosynthesis (Pn) have proven an effective technique for fruit thinning. Pesticides can be detrimental to plant growth by Pn reduction. A two-part study was developed to measure plant response to foliar applications of sulfur compounds. In study 1, 2% concentrations of various sulfur compounds were observed for potential physiological or pesticidal effects. Foliar treatments were applied to vegetative apple trees grown under controlled environment conditions to study photosynthetic effects. No treatments significantly reduced CO2 assimilation (A) and stomatal conductance (gs). Copper sulfate, ammonium sulfate, and potassium sulfate significantly reduced evapotranspiration (Et) 7 days after treatment. No significance was observed for plant growth. In study 2, a 2% potassium sulfate concentration significantly reduced A 22 days after treatment; however, no differences were observed for Et and gs. Differences in plant growth were not significantly different among treatments.
The relationship of variability in flowering and fruiting habit to canopy position and changing diurnal light and photosynthetic pattern was examined in 7 mature spur-type `Red Delicious'/MM106 apple trees. A .5×.5m column was placed in the north, south, east and west sections of tree canopies. Columns were subdivided by height with 3 study areas located at .25-.5m, 1.0-1.25m and 1.75-2.0m from the top of the canopy. In each, section, flowering index, fruit set, individual fruit weight and size, skin coloration, fruit soluble solids content, spur leaf area and spur bud diameter were determined. Photosynthetically active radiation and photosynthesis were measured from bloom through harvest correlated with variability in flowering, fruiting, spur quality and distribution of growth.
Osmotic agents used to prevent apple pollen grain germination were studied in vitro by applying 10 μL of solutions to germinating apple pollen on germinating and growth media. Seven concentrations (0%, 0.25%, 0.5%, 1%, 2%, 5% and 10%) of the solution were prepared for each chemical and the characteristics of pH, EC, and osmotic potential were measured. Apple pollen was dispersed onto the media in petri dishes. Micro drops of solution were then applied to marked areas. Dishes were then placed in germination cabinets at 25 °C. Cumulative percentage pollen germination was calculated 4, 8, 12, and 24 h after treatment by microscopic observation. Generally, the cumulative percentage pollen germination decreased asymptotically with increasing chemical concentration. The most effective chemicals for restricting pollen germination and growth were CuSO4 (0.25%), CH3 COOH (0.25%), CaCl2 (10%), K2 S2 O5 (0.25%), Methyl Jasmonate (2%). The effect of these chemicals has also been tested on pistil viability both in vitro and on excised limbs.
Since the passage of the Organic Foods Production Act in 1990, certified organic produce has begun to make a large impact on national markets. However, USDA statistics indicate that many states in the southern region have considerably reduced certified organic acreage when compared to other regions in the United States. The absence of organic acreage may perhaps originate with a lack of training and educational materials provided to producers due to unanticipated growth of organic markets. A thorough review of all Arkansas Cooperative Extension Service (ACES) materials, such as bulletins, publications, and workshops over the past 10 years, would reveal what information has been provided to producers on certified organic production. This review of ACES materials defines the existing groundwork on which ACES could construct future organic publications and outreach programs in order to sustain and stimulate organic farming within the state.
`Empire', `Smoothee', `Jonagold', and `Rome Beauty' apple cultivars (CV) on five size-controlling rootstocks, Bud.9, M.9 EMLA, M.26 EMLA, Mark, and Ott.3, were planted in Fayetteville, Ark., in 1990 as a complete block design with six replications. Although interactions for several growth variables were observed in 1990–93, there were no cultivar–rootstock interactions in 1994, 1995, or for cumulative yield. After six seasons' growth, CV did not significantly affect any growth variable. Trees on M.26 and M.9 were the largest, while trees on Mark were significantly smaller for both tree height and TCA; trees on Ott.3 and Bud.9 were intermediate. `Smoothee' had the greatest cumulative yield, while both `Jonagold' and `Rome Beauty' had significantly less; `Empire' yield was intermediate. Trees on Ott.3 and M.26 had larger cumulative yields than other stocks, which were all similar. Trees on Mark had the greatest yield/TCA, while M.9 and M.26 had the least yield/TCA; Ott.3 and B.9 were intermediate. Trees on Mark had very high levels of foliar Mn and exhibited symptoms of Mn-induced internal bark necrosis.
The Arkansas apple breeding program began in 1966 with objectives to develop high quality, dual purpose, adapted cultivars with a range of harvest dates and resistance to spring diseases. The program has two goals: 1) to develop red colored apples which are large, tart, firm and ripen between June and August; and, 2) develop yellow apples as a replacement for `Golden Delicious' which are large, typey, without russet and with a range of maturities from July through September. Apples with commercial potential are AA-18 (red, ripens 1-July), AA-44 (red, ripens 15-July), AA-58 (yellow, ripens 29-Aug.), AA-65 (yellow, ripens 11-Sept.) and AA-62 (yellow, ripens 15-Sept.). Data on time of bloom, harvest, fruit size, and fruit storage tests will be presented.