In 1984 trees of `Starkspur Supreme Delicious' apple on 15 rootstocks were planted at 28 locations in North America according to guidelines established by The North Central Regional Cooperative Project (NC-140). The largest trees were on P.18, ANT.313, B.490 and seedling. Producing trees approximately 70% the size of seedling were rootstocks P.1 and M.7 EMLA while M.26 EMLA and C.6 were 50% the size of seedling. A group of rootstocks 30% the size of seedling or smaller were B.9, MAC.39, P.22, P.2, P.16. Rootstocks with high production efficiency were P.16, 8.9, P.22, P.2 and C.6. Rootstocks with low production efficiency similar to apple seedling were MAC.1, M.4., B.490, P.18 and ANT.313.
D.C. Ferree and M. Knee
`Smoothee Golden Delicious' apple trees on nine rootstocks or interstems were mechanically root pruned annually for 9 years beginning the year after planting. Root pruning reduced trunk cross-sectional area (TCA) by 14% over the first 5 years and 22% in the last 4 years of the trial. Yield and fruit size were reduced by root pruning in most years with the fruit size effect obvious in June at the end of cell division. Interstem trees of MAC.9/MM.106 were larger than trees on M.9 and the following interstems: M.9/MM.106, M.9/MM.111, M.27/MM.111. Trees on seedling (SDL) rootstock were the largest and had the lowest yield per unit TCA and lower cumulative yield/tree than trees on M.7, MM.106, and MM.1ll. There was no interaction for any measure of growth or yield between root pruning and rootstock or interstem.
D.C. Ferree and J.G. Streeter
Container-grown `Chambourcin' grapevines were exposed to soil compaction created by changing soil bulk density to determine the effect of levels of compaction, rootstocks and moisture stress on mineral nutrition, leaf gas exchange and foliar carbohydrate levels. Shoot growth, leaf area, number of inflorescences and leaf dry weight decreased linearly as soil bulk density increased with the effects being significant above 1.4 g·cm-3. The early season leaf area was reduced 40% in the second season, but later leaves were unaffected by a soil bulk density of 1.5 g·cm-3. Net photosynthesis (Pn) and transpiration (E) increased linearly with increasing soil bulk density the first year, but the second year a nonlinear pattern was observed with highest rates at 1.3 and 1.4 g·cm-3. Soil bulk density of 1.5 g·cm-3 reduced number of leaves, leaf area and shoot length and advanced bloom 16 days on `Chambourcin' vines on six rootstocks with no interaction of rootstock and soil compaction. Withholding water for 8 days reduced Pn and E in all treatments, with no effect on shoot length, leaf, stem and total dry weights. Moisture stress in the noncompacted soil caused a reduction in leaf concentration of fructose, glucose and myo-inositol, but moisture stress had no effect in the compacted soil. Moisture stress caused a reduction in sucrose in both compacted and noncompacted soil. Compacting soil to a bulk density of 1.5 g·cm-3 was associated with an increase in leaf N, Ca, Mg, Al, Fe, Mn, Na, and Zn and a decrease in P, K, B, and Mo.
S.J. McArtney and D.C. Ferree
Dormant, 2-year-old, own-rooted `Chambourcin' grapevines (Vitis sp.) were subjected to two levels of root pruning (none, two-thirds roots removed) and were subsequently trained with either one or two canes. Vines were destructively harvested at bloom and after harvest when dormant to determine the effect of stored reserves in the root and competition between shoots for these reserves on vine growth and berry development. Removing 78% of the root system reduced shoot elongation and leaf area more effectively than did increasing the number of shoots per vine from one to two. Root pruning reduced the elongation rate of shoots for 45 days after budbreak, whereas increasing the shoot number reduced the shoot elongation rate for only 20 days after budbreak. A positive linear relationship was observed between leaf area per shoot at bloom and the number of berries per single cluster. These results demonstrate the importance of 1) the roots as a source of reserves for the initial development of vegetative tissues in spring, and 2) the rapid development of leaf area on an individual shoot for high set of grape berries on that shoot.
N.G. Krohn and D.C. Ferree
Greenhouse and field-grown `Seyval blanc' grapevines (Vitis sp.) were grown with low-growing, shallow-rooted, mat-forming, ornamental perennial groundcovers, and the effect of the groundcovers on the vegetative and fruiting growth of the grapevines was evaluated. The groundcovers used in this experiment were `Kentucky-31' tall fescue (Festuca arundinacea); white mazus (Mazus japoonicus albus); english pennyroyal (Mentha pulegium); dwarf creeping thyme (Thymus serpyllum minus); strawberry clover (Trifolium fragiferum); `Heavenly Blue' veronica (Veronica prostrata `Heavenly Blue'); and a companion grass mixture of 75% perennial ryegrass (Lolium perenne) and 25% red fescue (Festuca rubra). A control treatment grown without any groundcover was also used in both the greenhouse and field experiments. All of the groundcovers reduced `Seyval blanc' total shoot length from 22% to 85% in the vineyard. Cluster size was reduced in the field from 7% to 68% by the groundcovers compared to the herbicide control treatment, and from 9% to 66% in the greenhouse experiment, but none of the groundcovers in either the greenhouse or field experiments affected the pH, total acidity, or soluble solids concentrations of the `Seyval blanc' juice. English pennyroyal was the only groundcover that reduced in the leaf area of the grapevine. Single-leaf photosynthesis of the `Seyval blanc' grapevines in the field experiment was reduced by all groundcovers except mazus and creeping thyme. Water infiltration rates were 10 to 50 times higher in the groundcovers compared to the bare soil of the herbicide control treatment. Weed growth in the field caused reduction in shoot length similar to the most competitive groundcovers. Weed growth was reduced in the early season by the english pennyroyal and companion grass, and in the late season by all groundcovers. The reduction in growth of the grapevines caused by groundcovers in the greenhouse was a reasonable screen for the affect of groundcovers in the field. The mazus treatment was the only groundcover in our experiments that coupled fast growth with low competitive ability.
D.C. Ferree, D.M. Scurlock and J.C. Schmid
`Seyval blanc' and `Vidal blanc' grapevines (Vitis sp.) grown in large containers were root-pruned at different severities and/or stages of development and the effects on growth of both cultivars and fruiting of `Seyval blanc' were determined. As the severity of root pruning increased, stomatal conductance (g s) and transpiration (E) decreased and the number of wilted leaves increased in both cultivars. In both cultivars, root pruning reduced net photosynthesis (Pn) and E for as long as 18 to 20 days, as well as total leaf area and dry weight of leaves and petioles plus tendrils. The reductions were proportional to the degree of root pruning. A similar pattern existed for cane and root tissue of `Vidal blanc'. As the severity of root pruning increased, berry and cluster weight, and titratable acidity (TA) of `Seyval blanc' decreased. There was no effect of root pruning on berries per cluster, soluble solids content (SSC), or pH of the juice. No interaction was significant for any factor between time of root pruning and fruiting measured on `Seyval blanc' vines. Root pruning at bloom reduced leaf area, number of leaves, and dry weight of petioles, trunks, and canes. Root pruning at veraison had no effect on any vegetative or fruit parameters. Fruiting `Seyval blanc' vines had less leaf area and smaller petiole and cane dry weights than did nonfruiting vines.
D.C. Ferree, S.J. McArtney and D.M. Scurlock
Vines of container grown `DeChaunac', `Vidal blanc', `Seyval blanc' and `Chambourcin' grapes were subjected to 5 days of 80% shade at prebloom, bloom or 2 and 4 weeks after bloom. Fruit set, cluster weight, berries per cluster and juice components [soluble solids concentration (SSC), pH and titratable acidity] of `DeChaunac' and `Vidal blanc' were not affected by a short period of intensive shade. `Chambourcin' was sensitive to a shade period near the time of bloom for most of the aforementioned factors, while `Seyval blanc' was intermediate in sensitivity. Shot (green, hard, and undersized) berries of `Chambourcin' and `Seyval blanc' were increased by a 5-day period of shade 2 or 4 weeks after bloom. In a second study, container-grown `Chambourcin' on 3309C (V. riparia × V. rupestris) with one or two clusters and `Vidal blanc' with one cluster were subjected to the following light regimes beginning at bloom for 5 weeks: supplemental light, ambient greenhouse light and 30%, 50% or 80% shade. Yield, fruit set, specific leaf weight (leaf dry weight/leaf area), saturation index, and total leaf chlorophyll increased linearly with increasing irradiance. `Chambourcin' juice pH, SSC, leaf chlorophyll a/b ratio, cluster color development and hue angle decreased as irradiance increased, likely related to crop reduction. Responses in `Vidal blanc' followed similar trends, but differences were not as great. Results demonstrate that light is an important determining factor in fruit set of French-American hybrid grapes and fruit set of some cultivars are sensitive to short periods of intense shade.
D.C. Ferree, J.C. Schmid and B.L. Bishop
Survival of replicated rootstock plantings of apple trees (Malus ×domestica) to fire blight (Erwinia amylovora) infection shows that a wide range of rootstock susceptibility exists. Trees on `Malling 26' (M.26), `Malling 9' (M.9), and `Mark' consistently had significant losses. Of the dwarfing rootstocks widely available commercially, `Budagovsky 9' (B.9) survived well with productive trees, but was not resistant to fire blight infection. The following experimental rootstocks had good survivability with many live productive trees in one or more trials: `Poland 2' (P.2), `Vineland 1' (V.1), `Malling 27 EMLA' (M.27 EMLA), `Budagovsky 491' (B.491), `Budagovsky 409' (B.409), `Vineland 7' (V.7), `Vineland 4' (V.4), and `Oregon Rootstock 1' (OAR1).
W.C. Olien, D.C. Ferree and B.L. Bishop
Rootstock recommendation is complicated by performance-site interactions. The N C140 Regional Project recently completed a lo-year evaluation of 9 rootstocks in locations across North America. Based on this data, we developed stability analysis models and demonstrated significant rootstock-site interactions for cumulative yield (CY) and trunk cross-sectional-area (CSA). The models require a site index (SI) estimated from mean performance over rootstocks within site. Prediction of rootstock performance in untested sites would be possible with an independent estimate of SI. We tested prediction of SI from mean maximum temperature (T) and total moisture received (M) and divided T and M into 5 phenological periods: Dee-Jan (Dormant), Feb-Apr (Prebloom), May-Jun (fruit Set), July-Sept (fruit Growth), and Oct-Nov (Postharvest). SICSA was not predicted by any T or M variable. SICY was predicted by TSet. TGrow, and MSet, but TSet and MSet were codependent. SICY was best predicted from a linear relationship with TSet.
D.C. Ferree, J.G. Streeter and Y. Yuncong
Container-grown apple (Malus ×domestica Borkh.) trees were exposed to soil compaction created by changing soil bulk density (SBD) to determine the effect of compaction levels, rootstock, and moisture stress on mineral nutrition, leaf gas exchange, and foliar carbohydrate levels. With SBD of 1.0, 1.2, and 1.4 g·cm-3, there was no interaction of rootstock and soil compaction for growth of `Melrose' trees on nine rootstocks. Trees grown in a SBD of 1.2 g·cm-3 had a greater dry weight than trees at 1.4 g·cm-3 bulk density. Increasing SBD to 1.5 g·cm-3 reduced shoot length, total leaf area, leaf size, and dry weight of leaves, shoots, and roots. The interaction between rootstock and SBD was significant and total dry weight of `B.9', `G.16', `G.30', and `M.7 EMLA' was less influenced by 1.5 g·cm-3 soil than trees on `M.26 EMLA' and `MM.106 EMLA'. Withholding moisture for 10 days at the end of a 70-day experiment caused 8% to 25% reduction in growth in a non-compacted (1.0 g·cm-3) soil with much less effect in a compacted soil. Prior to imposing the moisture stress by withholding water, net photosynthesis (Pn) was reduced 13% and transpiration (E) 19% by increasing bulk density to 1.5 g·cm-3. Following 7 days of moisture stress in non-compacted soil, Pn and E were reduced 49% and 36%, respectively, with no such reductions in the compacted soil. Increasing SBD to 1.5 g·cm-3 caused a decrease in the leaf concentration of quinic acid, myoinositol, and sucrose and an increase in fructose and glucose. Trees growing in 1.5 g·cm-3 had reduced concentrations of N, Ca, Mg, Mn, Na, and Zn, and increased P, K, B, and Fe in leaves.