Calcium is commonly known to affect the developmental processes of many plants, and its role as a major nutrient has been interpreted in terms of its interaction with components of the cell wall and membrane. A 2-year study was conducted to assess the affects of calcium foliar feed fertilization applied at bloom and throughout floral development on the reduction of rain-related splitting in blueberries. Foliar-applied calcium at 0.2% or 0.9% concentration did not successfully decrease splitting in blueberries to a statistical and, more importantly, an economically significant level. Calcium sprays also had no adverse affects on the fruit firmness, quality, or calcium concentrations within the fruit.
Donna A. Marshall, James M. Spiers and Kenneth J. Curry
H. Y. Hanna and A. J. Adams
Seaweed extract has been reported to have various beneficial effects on many crops. A study was conducted in 1989 and 1990 to evaluate the effects of Response 9-9-7, a seaweed extract fortified with NPK, on yield of staked tomatoes and cucumbers. Plants were sprayed to the runoff weekly, biweekly, every 3 weeks and every 4 weeks with 1:500, 1:250, 1:150 and 1:125 v/v Response/water respectively. Results indicate that spring tomatoes sprayed with Response 9-9-7 at all rates outyielded the check which was sprayed with plain water. However, the only significant difference was obtained when tomatoes were sprayed with 1:150 Response/water in 1989 and 1:500 in 1990. Response/water at 1:500 rate significantly increased the quality and marketable yield of cucumber in both years. Response 9-9-7 had no effect on yield of tomatoes grown in the summer under heat stress.
Raul I. Cabrera, James A. Reinert and Cynthia B. McKenney
Field (choice) and laboratory (no choice) studies were conducted to evaluate the susceptibility of 12 crape myrtle (Lagerstroemia) cultivars, representing two species and their interspecific hybrids, to feeding damage by the flea beetle (Altica litigata Fall). The results indicate that as a group, the L. indica L. cultivars were more susceptible to attack and significant herbivory damage by Altica beetles, whereas all the L. fauriei Koehne cultivars and most of the interspecific L. indica × fauriei hybrids were resistant. Significant differences in feeding damage were observed between the new and older leaves in the susceptible hybrid ‘Biloxi’ and L. indica ‘Whit IV’, but not in the rest of the cultivars. Mineral nutrient content differences were observed between species with L. indica cultivars having a significantly contrasting nutrient status profile compared with the L. fauriei and interspecific hybrid cultivar groups. The results indicate that the factors influencing Altica flea beetle-feeding preferences and damage are inherited and therefore will allow the implementation of pest management practices that minimize damage and optimize chemical control strategies. In addition, opportunities may exist for breeding and selection efforts that could lead to superior cultivars with insect resistance.
Bernadine Strik, Timothy Righetti and Gil Buller
Fertilizer nitrogen (FN) recovery, and changes in nitrogen (N) and dry weight partitioning were studied over three fruiting seasons in June-bearing strawberry (Fragaria ×ananassa Duch. `Totem') grown in a matted row system. Fertilizer nitrogen treatments were initiated in 1999, the year after planting. The standard ammonium nitrate N application at renovation (55 kg·ha-1 of N) was compared to treatments where additional N was applied. Supplemental treatments included both ground-applied granular ammonium nitrate (28 kg·ha-1 of N) applied early in the season and foliar urea [5% (weight/volume); 16 kg·ha-1 of N] applied early in the season and after renovation. When labeled N was applied (eight of nine treatments) it was applied only once. The impact of no FN from the second through the third fruiting season was also evaluated. Fertilizer nitrogen treatment had no impact on total plant dry weight, total plant N, yield or fruit quality from the first through the third fruiting seasons. Net dry matter accumulation in the first fruiting season was 2 t·ha-1 not including the 4 t·ha-1 of dry matter removed when leaves were mowed during the renovation process. Seasonal plant dry weight and N accumulation decreased as the planting aged. Net nitrogen accumulation was estimated at 40 kg·ha-1 from spring growth to dormancy in the first fruiting season (including 30 kg·ha-1 in harvested fruit, but not including the 52 kg·ha-1 of N lost at renovation). Recovery of fertilizer N ranged from 42% to 63% for the broadcast granular applications and 15% to 52% for the foliar FN applications, depending on rate and timing. Fertilizer N from spring applications (granular or foliar) was predominantly partitioned to leaves and reproductive tissues. A large portion of the spring applied FN was lost when plants were mowed at renovation. Maximum fertilizer use efficiency was 42% for a granular 55 kg·ha-1 application at renovation, but declined to 42% just before plant growth the following spring, likely a result of FN loss in leaves that senesced. In June, ≈30% of the N in strawberry plants was derived from FN that was applied at renovation the previous season, depending on year. This stored FN was reallocated to reproductive tissues (22% to 35%) and leaves (43% to 53%), depending on year. Applying fertilizer after renovation increased the amount of remobilized N to new growth the following spring. The following June, 15% of plant nitrogen was derived from fertilizer applied at renovation 2 years prior.
J. R. Davenport
Foliar feeding of crop plants is an increasingly popular practice. The use of foliar nutrients relies on the ability of the plant to sorb nutrients through the leaves. Cranberries (Vaccinium macrocarpon Ait.) are known to have a waxy cuticle on the leaf surface which may impede nutrient uptake, leaving only the lower leaf surface for effective uptake. This study was undertaken to determine the extent of foliar nutrient uptake by cranberries using rubidium as a tracer. Rubidium was chosen for its similarity to potassium in plant uptake. In replicated plots, cranberries were sprayed with rubidium at the rate recommended for foliar potassium at three different growth stages and three different times of day. Washed and unwashed leaves were analyzed one day, one week, and one month after rubidium applications. Stem, soil, and root material was analyzed for rubidium at the one week and one month sample times. Results will be discussed with reference to uptake and movement of foliar applied nutrients in cranberries.
Bruce W. Wood and Charles C. Reilly
Foliar feeding by the black pecan aphid [Melanocallis caryaefoliae (Davis)] can cause tremendous economic losses. Evaluations of black aphids on pecan genotypes indicates that both antixenosis and antibiosis-like resistance mechanisms exists. Tests for antixenosis indicated that aphids possess clear preferences for certain genotypes over others and that this preference can be dependent on a water-soluble chemical component of the leaf surface. Aphids also exhibited a “conditioning preference,” in which they preferentially feed on genotypes from which they originated. Antibiosis tests indicated that pecan genotypes influence the reproductive success of aphids already possessing a feeding adaptation to those same pecan genotypes; therefore, an evaluation of 30 cultivars for antibiosis indicated that populations developed only 20% as fast on `Choctaw' and `Alley' as on `Desirable' and `Success'. No cultivar was observed to essentially prevent aphid reproduction.
Huangjun Lu, Alan L. Wright and David Sui
( Da Costa and Jones, 1971 )], common bean [ Phaseolus vulagaris ( Cardona et al., 1982 )], sweetpotato [ Ipomoea batatas ( Schalk et al., 1986 )], and soybean [ Glycine max ( Layton et al., 1987 )]. Foliar feeding on lettuce by BCB adults leads to
Scott C. Redlin, Dale E. Herman and Larry J. Chaput
to Pests and Stress Evaluations indicate that ‘SunDak’ has resistance to ash/lilac borer [ Podosesia syringae (Harris)] and powdery mildew [ Microsphaera penicillata (Wallr.: Fr.) Lév.]. It is not susceptible to foliar feeding insects. It is
Frank G. Bethea Jr., Dara Park, Andrew Mount, Nick Menchyk and Haibo Liu
that adding a surfactant aided uptake of urea, even at 50% ET level, and it could be considered a good practice to include a surfactant when foliar feeding mildly water-stressed turf. Recommendations include applying solutions when bentgrass is being
Sanjun Gu and Kirk W. Pomper
. Publ., Columbus, OH Boucher, T.J. Pfeiffer, D.G. 1989 Influence of Japanese beetle (Coleoptera: Scarabaeidae) foliar feeding on ‘Seyval Blanc’ grapevines in Virginia J. Econ. Entomol. 82 221 224