Foliage Treatment Research Articles

Enhancing cropping of Navel orange by different agrochemicals<br>foliar sprays

The present investigation was carried out during the two successive growing seasonsof 2003 and 2004 on Washington Navel orange trees grown at El-Tarh region, El-BeheraGovernorate of Egypt. In order to study the effect of spraying the trees with differentagrochemicals on vegetative growth, fruit drop, fruit retention and yield. Trees were divided intotwo groups , the first group was subjected to the foliage treatments when the fruit reached pea size(5 mm in diameter) and the second group at marble size (15 mm in diameter). Foliar sprays ofurea or 2, 4-D alone at pea or marble stage significantly increased vegetative growth. In general,foliar sprays of 2, 4-D alone or with the different calcium compounds at pea or marble stagesignificantly increased fruit retention and decreased fruit drop after June drop. Final fruit retentionwas increased (23 - 69% over the control) and pre-harvest fruit drop was decreased (63 to 100%compared to the control) by spraying boric acid or 2, 4-D alone at the pea stage in both seasons.Spraying calcium superphosphate alone at the marble stage caused an increase in final fruitretention by 33 - 7% and a decrease in pre-harvest fruit drop by 61 -72% over the control in bothseasons.

Effect of a strobilurin-class fungicide on water use in synthetic bread wheat genotypes grown under increasing water deficit conditions

Three synthetic bread wheat genotypes and their parental cultivar Cham 6 were used to examine the effects of a strobilurin-class fungicide pyraclostrobin on leaf temperature, root water uptake and grain yield under increasing water deficit conditions. Wheat plants of Cham 6 treated with the pyraclostrobin at the booting stage showed a rapidly increased leaf temperature as compared with the gradually increased leaf temperature of the untreated plants. The final temperature reached, however, was lower for the pyraclostrobin treated plants than the untreated. Potted soil of the treated wheat plants also showed higher water contents than the untreated potted soil, suggesting delay of plant water uptake by pyraclostrobin treatment. A variation in water uptake by roots was also found between the four wheat genotypes examined. Daily water uptake was depressed after the pyraclostrobin treatment in all four wheat genotypes. Grain yields were slightly increased by the pyraclostrobin treatment in field trials under controlled water supply whereas no significant differences were detected in soil water content between treatments. The increase in grain yield by pyraclostrobin treatment might be dependent on the different water uptake of the wheat genotypes. These results suggest that foliage treatment of pyraclostrobin fungicide on wheat delays root water uptake, resulting in postponement of soil dehydration, which contributes to a slight increase of grain yield in some wheat genotypes in the field under water deficit conditions.

Improved global simulations of gross primary product based on a separate and explicit treatment of diffuse and direct sunlight

For computational expediency, regional and global land‐surface models (LSMs), especially those coupled to climate simulations, adopt simple algorithms when calculating radiative transfer (RT) and canopy photosynthesis at the vegetated land surface. Nevertheless, the interaction of sunlight with vegetation is recognized as one of the most critical processes represented in LSMs. The present study calculates global, terrestrial Gross Primary Product (GPP) with a version of the land‐surface model JULES which has been modified to take explicit account of sunfleck penetration and leaf orientation within the canopy. A comparison with equivalent simulations adopting the Big Leaf (BL) or two‐stream (2ST) RT scheme, indicate that current regional/global LSMs may overestimate GPP by 10% globally and up to 25% regionally. Specifically, their use of average light profiles, and consequent neglect of the dispersion in leaf irradiance, at any given height in the canopy leads to both a general overestimation of canopy light‐use efficiency (LUE) and a failure to capture the LUE‐enhancement under diffuse sunlight (“diffuse fertilization effect”). We also examine the current limitations of regionally/globally implemented RT schemes with respect to canopy architecture. This is done by coupling JULES to the ray‐tracing numerical model FLIGHT, the latter simulating light transfer and photosynthesis in both uniform one‐dimensional (1‐D) canopies and 3‐D tree crowns. When the distribution of leaf nitrogen (N) is configured in a manner consistent with field measurements, output from the 3‐D and 1‐D FLIGHT simulations is fairly similar (predicted GPP differs by ≤5%). Similarly, both Leaf Angle Distribution (LAD), when restricted to its observed range, and leaf‐clumping appear to have a minor influence over canopy productivity. We conclude that current LSMs can radically improve their calculation of regional/global GPP by adopting a multilayer approach. This will allow the separate treatment of sunlit and shaded foliage, at discrete heights within the canopy, as well as the accurate representation of active leaf‐N.

Comparison of strains of Lysobacter enzymogenes and PGPR for induction of resistance against Bipolaris sorokiniana in tall fescue

Abstract Lysobacter enzymogenes C3, the only biocontrol agent previously known to induce resistance in tall fescue against Bipolaris sorokiniana, was compared in growth chamber experiments with other strains of L. enzymogenes, strains of plant growth promoting rhizobacteria (PGPR) that induce systemic resistance in dicot plants, and the synthetic elicitor 1,2,3-benzothiadiazole-7-thiocarboxylic acid-S-methyl-ester (BTH). The treatments were evaluated for induction of localized or systemic resistance against B. sorokiniana when applied to leaves and roots. In addition, the effects of induced resistance on pathogen conidial germination on the phylloplane were assessed. None of the bacterial or chemical treatments induced systemic resistance when applied to a leaf. Strains of L. enzymogenes differed in their ability to cause localized disease inhibition following foliage treatment and to induce systemic resistance in leaves when applied to roots. In contrast to C3, two other strains of L. enzymogenes were ineffective in inducing systemic resistance. PGPR strains varied in effectiveness in causing localized disease inhibition when applied to leaves. Most of the bacterial strains increased peroxidase activity in the treated leaves, providing evidence that localized disease inhibition may have been plant mediated. The involvement of localized induced resistance was confirmed in P. fluorescens WCS417r, which did inhibit B. sorokiniana conidial germination or hyphal growth in vitro. Soil drenches with nearly all PGPR strains resulted in systemic resistance in leaves, but the treatments varied as to the timing and strength of induced systemic resistance. BTH induced localized resistance when applied to leaves but did not activate resistance in leaves when applied to roots. All cases of induced resistance were associated with an inhibition of conidial germination on leaf surfaces and, thus, this reaction appears to be a hallmark of induced resistance in the B. sorokiniana-tall fescue pathosystem.

Influence of exogenous gibberellin inhibitors on tuber sprouting in yam

AbstractTo induce sprouting two gibberellin inhibitors, uniconazole‐P (UP) and prohexadione‐calcium (PC), were applied to foliage of white Guinea yam (Dioscorea rotundata) and water yam (D. alata) 30 days before harvest or to tubers at harvest. The tuber sprouting period was shortened by about 35 days in D. alata TDa 95/00328 in response to UP and PC, and TDa 92‐2 in response to PC, but not in others through foliage treatment. Sprouting of tubers was promoted in D. rotundata TDr 99‐12 and D. alata TDa 99/00049 and TDa 291 when they were soaked in UP or PC, but the others had a limited response at harvest. Sprouting of TDa 99/00049 tubers started 70 days earlier and the periods of sprouting were 35 to 42 days shorter in response to the UP and PC. Foliar application was more effective in promoting tuber sprouting than tuber soaking at harvest in TDa 92‐2 and TDr 93‐31, and the reverse was true for TDr 99‐12 and TDa 291. The responses of yam varieties to UP and PC seem to vary depending on the stage of dormancy in their tubers. Copyright © 2003 Whurr Publishers Ltd

Effects of Diflubenzuron onPseudoplusia includens(Lepidoptera: Noctuidae) and its ParasitoidCopidosoma floridanum(Hymenoptera: Encyrtidae)

The insect growth regulator (IGR), diflubenzuron (Dimilin 2L), was evaluated for its effect on development of Copidosoma floridanum (Ashmead) and its host, Pseudoplusia includens (Walker), when applied at 0.035 kg ai/ha to soybean, Glycine max (L.), a rate used in preventive programs for control of velvetbean caterpillar, Anticarsia gemmatalis Hubner. Parasitized and nonparasitized soybean looper larvae were fed either diflubenzuron-treated or nontreated foliage. The feeding period of parasitized larvae was 1.7 and 1.8 d longer on diflubenzuron-treated and nontreated foliage, respectively, than that of nonparasitized larvae. Pupation period of C. floridanum and soybean looper was not significantly influenced by diflubenzuron. Although parasitized soybean looper fed both foliage treatments experienced 100% mortality, nonparasitized soybean looper fed nontreated foliage was 23.2% and nonparasitized soybean looper fed diflubenzuron-treated foliage was 12.2%. Parasitized soybean looper fed nontreated foliage consumed 19.2% more leaf area than nonparasitized larvae fed nontreated foliage, whereas parasitized soybean looper fed diflubenzuron-treated foliage consumed 21.2% more leaf area than nonparasitized larvae on the same foliage. There was no significant difference in number of parasitoids emerging from host mummies among treatments; however, there was a positive correlation between leaf area consumed and adult parasitoids per mummy. Diflubenzuron does not appear to produce deleterious effects in C. floridanum or its host, soybean looper, at the current rate used for management of other lepidopteran pests.

Gas exchange and hydraulic properties in the crowns of two tree species in a Panamanian moist forest

Hydraulic properties and gas exchange were measured in branches of two tropical tree species (Simarouba amara Aubl. and Tapirira guianensis Aubl.) in a moist lowland forest in Panama. Branch-level sapflow, leaf-level stomatal conductance, and water potential measurements, along with measurements of specific hydraulic conductivity of stems in crown tops, were used to relate hydraulic parameters to leaf conductance in two individuals of each species. Branches of the taller trees for each species (28 m, 31 m) showed much higher leaf-specific hydraulic conductance and leaf vapor-phase conductance than those of the smaller trees (18m, 23m). This was probably related to the leaf-to-sapwood area ratio in branches of taller trees, which was less than half that in branches of smaller trees. Dye staining showed evidence of massive cavitation in all trees, indicating that stomata do not control leaf water potential to prevent xylem cavitation in these species. Stomatal conductance of intact leaves also appeared to be insensitive to leaf area removal treatment of nearby foliage. Nevertheless, a simple mass-balance model of water flux combining hydraulic and vapor transport was in close agreement with observed maximal vapor-phase conductance in the four trees (r2=0.98, P=0.006). Our results suggest that the major organismal control over water flux in these species is by structural (leaf area) rather than physiological (stomatal) means.

Factors Influencing Water Split of Pecan Fruit

Water stage fruit split (WS) is an erratic and complex problem often causing major crop losses to susceptible pecan [Carya illinoinensis (Wangenh.) K. Koch] cultivars. This study identified two episodes of WS for `Wichita' pecan—a highly susceptible cultivar. The previously recognized precipitation-induced fruit splitting is the major episode; however, a previously unrecognized precipitation-independent, minor episode can also occured before the major episode. This minor episode was associated with the low solar irradiance and high relative humidity—conditions commonly associated with August rains. The crop characteristics of affected trees also influenced WS in that WS increased as crop load per tree increased. Fruits were also more likely to exhibit WS if located within the lower tree canopy. Treatment of foliage with an antitranspirant immediately before split-inducing conditions increased WS. Maintenance of moist soils for ≈2 weeks before WS-inducing conditions substantially reduced WS-related crop losses. These findings help to explain the erratic nature of WS and indicate that maintenance of trees in a well-watered state for ≈2 weeks before the initiation of shell hardening may substantially reduce WS-related crop losses in certain years.

Reduction of Tomato Early Blight by Combining Soil Solarization and Biological Control Strategies

Combinations of solarized soil (SBS), bare soil control (BS), black plastic mulched soil (BM), row cover (RC), fungicide (chlorothalonil) and biological treatments (Bacillus cereus) were evaluated. SBS vs. BS treatments were main plots, mulch and row covers splitplots and foliage treatments split-splitplots. Application of either foliar treatment was superior to BS. Using a 1/2 rate of fungicide on plants from solarized soil treatments showed equal or comparable reduction of the disease when compared to tomatoes grown in BS with high rates of the fungicide. Combined treatments of solarized + BM, BM with or without RC and low rate of fungicide or biological agent, were the most effective when compared to BS + fungicide, indicating that integration of plasticulture and biological strategies can reduce early blight below the levels of commercial fungicide applied to tomatoes grown on BS.

Simultaneous determination of tebufenozide and five of its intact metabolites from forestry matrices by high-performance liquid chromatography

A simple, rapid and reliable high-performance liquid chromatographic (HPLC) method for the determination of tebufenozide insecticide and five of its intact metabolites in spruce foliage, litter, forest soil, sediment and natural water is described. The fortified litter, soil and sediment samples were extracted with acidic methanol in presence of Celite and the aqueous phase was partitioned with dichloromethane (DCM) after the alcohol was removed. The residues in the DCM phase, after evaporation to dryness, were dissolved in an acetone-hexane mixture and cleaned by Florisil column. The treatment of spruce foliage was similar except that the acidic methanol was also partitioned with hexane prior to DCM extraction. Natural water was extracted with DCM and the residues were dissolved in methanol for HPLC analysis without any column cleanup. The chromatographic system consisted of an ODS Hypersil (5 μm) 250 × 4 mm I.D. column linked to a UV detector set at 236 nm. The mobile phase consisted of methanol-water with 0.005 M PIC A as an ion-pairing agent. Mean recoveries of the analytes, depending on their structure, ranged from 69 to 102% with standard deviations ranging from 5 to 8%. Limits of detection for the solid matrices ranged from 0.01 to 0.03 μg/g; for water it was 1.5 μg/l. The method was applied successfully to the analysis of field samples sprayed with tebufenozide.

Pyrethroids for Hickory Shuckworm and Pecan Nut Casehearer Control, 1990

Abstract The effect of pyrethroid insecticides over HSW and 1st and 2nd generation PNC were evaluated in Coahuila. Trials were conducted at Estancias and Parras de la Fuente, Coahuila under field conditions on 15-18 yr old Western pecan trees. A complete randomized block design was used consisting of 12 treatments: 3 doses of Ambush, Cymbush and Karate; one dose of Guthion and Zolone the most used insecticides as comparative checks and the unsprayed check, with 3 replicates and one tree/treatment/block. Foliage treatments were made on 7 May and 12 July for 1st and 2nd generation PNC and 12 Aug for HWS. Post-treatment counts were made 8 and 15 DAT. Sampling consisted on checking 25 nut clusters/tree for damaged nuts. Data were subjected to ANOVA and LSD tests.

Protective action of midgut catalase in lepidopteran larvae against oxidative plant defenses

Catalase activity was detected in the midgut tissues and regurgitate of several lepidopteran pests of the tomato plant. Greatest activity in the midgut was detected in larvalHelicoverpa zea, followed bySpodoptera exigua, Manduca sexta, andHeliothis virescens. We present evidence that catalase, in addition to removing toxic hydrogen peroxide, may inhibit the oxidation of plant phenolics mediated by plant peroxidases. Small amounts of larval regurgitate significantly inhibited foliar peroxidase activity via removal of hydrogen peroxide. Treatment of foliage with purified catalase nearly eliminated peroxidase activity and was superior as a larval food source compared to untreated foliage. Tomato foliar peroxidases oxidize an array of endogenous compounds including caffeic acid, chlorogenic acid, rutin, coumaric acid, cinnamic acid, and guaiacol. The oxidized forms of these compounds are potent alkylators of dietary and/or cellular nucleophiles (e.g., thiol and amino functions of proteins, peptides, and amines). When tomato foliar protein was pretreated with peroxidase and chlorogenic acid and incorporated in artificial diet, larval growth was reduced compared to larvae fed untreated protein. Thus, the diminution of peroxidase activity and removal of hydrogen peroxide by catalase may represent an important adaptation to leaf-feeding. The secretion of catalase in salivary fluid during insect feeding is also suggested to be a potential mechanism for reducing hydrogen peroxide formation as an elicitor of inducible plant defenses.

Stability of phenolic and protein measures in excised oak foliage

The stability of protein and phenolic measures in excised foliage from two oak species was measured under conditions that simulated the handling and treatment of foliage during insect rearing trials. Excised foliage kept hydrated under refrigeration or insect-rearing conditions maintained stable levels of protein content, proanthocyanidins, gallotannins, total phenolics, and protein-binding capacity for up to 48 hr following field sampling. Measures of protein content, total phenolics, protein-binding capacity, and proanthocyanidins were significantly greater 48-72 hr after field sampling, followed by declines to near field levels within 120 hr.

A comparison of foliar wettability of red spruce and balsam fir* growing at high elevation

summaryThe contact angle method was used to determine the wettability of red spruce (Picea rubens Sarg.) and balsam fir [Abies balsamea (L.) Mill.] foliage in subalpine sites (1010–1400 m above sea level) at three locations in northern New England, USA (Camels Hump in Vermont and Mt. Moosilauke and Mt. Washington in New Hampshire).The dependence of contact angle (θ) on foliage age (t, in months) could be expressed in the form θ=θ1+θ2 e−kt. The value of the decay constant (k) ranged from 0.02 to 0.12 (month−1), depending upon location, but was independent of elevation, canopy position, and, in most cases, species. The asymptotic value of the contact angle (θ1) i.e. that approached by very old foliage, did not differ between species at some sites but was greater in fir than in spruce at others. The value of θ1 decreased with elevation in both species and tended to increase with an increase in height within the canopy. The value of the component which affected contact angle variation with age (θ2) was always greater in fir than in spruce, but was unaffected by elevation; in fir, it appeared to increase with height in the canopy. Thus, the estimated value of the initial (t= 0) contact angle (θ1+θ2) was greater in fir, increased with height in the canopy, and decreased with elevation. The overall pattern found was that (1) young foliage of spruce is more wettable than young foliage of fir, but the difference becomes smaller in older age classes; (2) young foliage near the bottom of the canopy is more wettable than near the top; and (3) foliage from a given age class and species is more wettable at higher elevations.The treatment of foliage with xylene to remove epicuticular wax decreased contact angles of fir but increased them in spruce. Scanning electron microscopy revealed that wax removal by xylene did not mimic natural wax removal. Contact angles obtained with acidified water did not vary significantly from those obtained with deionized water.

Air Stream Facilitated Application of Cotton Foliage Treatments

ABSTRACT THE upper canopy of cotton foliage prevents sprayed droplets from reaching the lower leaves, and especially from reaching the undersids of lower leaves. An Air-sleeve sprayer, which uses a vertical air stream, was recently developed to achieve a uniform coverage of all the leaves and was very successful in controlling most insects in the field (Cohen et al., 1984). In the present study, an air-sleeve sprayer was compared to a hydraulic nozzle sprayer for droplets coverage, Bemisia Tabaci Gennadius control, and defoliation of cotton. The droplets coverage and defoliation results were better with the air-sleeve sprayer than with a hydraulic nozzle alone. However, no differences were detected between the two sprayers for Bemisia control.

Glyphosate–sediment interactions and phytotoxicity in turbid water

AbstractIn aquatic situations it was expected that adsorption by sediments and suspended solids would influence the movement of glyphosate away from the application zone and attenuate its phytotoxicity. However, the results of two experiments showed that only a minor proportion of glyphosate was adsorbed onto suspended solids, even in turbid irrigation water. Phytotoxicity, as measured by the effect on the root growth of safflower (Carthamus tinctorius L.), was not significantly reduced. Where glyphosate was intentionally injected into flowing water of contrasting quality to simulate incidental contamination of water during foliage treatment, adsorption by benthic sediments attenuated loads of glyphosate only slowly. The attenuation was 13–27% for each kilometre of travel downstream, as compared to 31% observed previously. However, when glyphosate was sprayed onto the sediment exposed after channel draining, less than 7% of the glyphosate applied was subsequently eluted. Consequently, draining before treatment should be an effective strategy for minimising the contamination of irrigation water.

Combined Effect of Disease and Herbicide Treatment on Yield of Sugarcane (Saccharum officinarum)

Sugarcane (Saccharum officinarumL.) was planted in the fall; the seed cane was healthy or infected either with sugarcane mosaic virus (strain H) or with ratoon stunting disease (RSD) (Clavibacter xyli). Herbicide treatments were applied the following spring and each subsequent spring during the 3-yr crop cycle. Hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] at 1.1 kg ai/ha was applied as a soil foliage treatment when sugarcane was about 30 cm tall. The methyl ester of diclofop {(±)-2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid} at 1.1 kg ai/ha and the sodium salt of asulam {methyl [(4-aminophenyl)sulfonyl] carbamate} at 3.4 or 3.8 kg ai/ha were applied as foliage treatments when sugarcane was about 90 cm tall. Both mosaic and RSD reduced yield of sugar/ha by 16% for the 3-yr crop, primarily by causing a decrease in stalk population. Hexazinone reduced yield of sugar/ha by 24% primarily by causing a decrease in both stalk population and sugar content of stalks. Diclofop reduced yield by 7% and asulam caused no significant yield loss. Combinations of disease and herbicide treatment reduced yields in an additive manner, with the combination of hexazinone and either mosaic or RSD causing a 38% reduction.

Relationship between cultural practices and the occurrence of volunteer potatoes in the Columbia Basin

The time of tillage practices following potato harvest in the Columbia Basin affected numbers of volunteer potato plants that emerged. The best control was achieved by waiting after harvest until tubers on the surface were frosted at least once and then plowed to expose additional tubers from below the frost. Planting a wheat cover crop after plowing further reduced numbers of volunteers. Foliage treatment with maleic hydrazide to prevent sprouting gave excellent volunteer control in one season and poor control the next. Soil fumigation with Telone C-17 gave excellent control of volunteers. Properly timed tillage combined with use of a wheat cover crop was as effective as the chemical treatments in reducing numbers of volunteers.

ミズガヤツリの生活過程の解析と防除に関する研究

The author investigated the physiological and ecological characteristics of C. serotinus, a perennial weed in paddy fields, during its whole life cycle, together with agronomic and chemical methods of control, and designed an effective integrated control system. This study was carried out at Chiba Agricultural Experiment Station during the period from 1966 to 1976.1. The life cycle is divided into 4 stages, emergence, propagation, tuber formation, and preparation for emergence. Reproduction occurs by seeds, tubers, base of shoots, base of new shoot-tubers, and stolon, but mainly by tubers.2. Characteristics and factors affecting tuber sprouting were analysed. The results indicated that oxygen supply is the most important factor for tuber sprouting, and that, in the fields, soil moisture content exerts an important influence on emergence from tubers in relation to oxygen supply.3. Effect of temperature, fertilizer elements and light on the propagation was examined. Results showed that competition for nutrients between rice plants and C. serotinus may be one of the reasons for the retarded propagation in rice fields, but the major limiting factor for the propagation of C. serotinus is presumed to be light intensity, since in any case the propagation was more inhibited when the growth of rice plant was more active compared to that of the weed.4. Factors affecting tuber formation were examined. Day-length as well as temperature was found to be an important factor affecting tuber formation, it appeared and that the number of tubers is determined by the number of plants, and also by the factors affecting propagation of plants.5. To analyse the effects of C. serotinus on growth and yield of rice, C. serotinus was planted at different times and different densities in paddy fields under various methods of rice cultivation. The results indicate that the dominancy of rice plants in the competition for light with C. serotinus causes less crop damage by the weed. The yield component which contributed most to the rice yield reduction was the decrease in panicle number, followed by the decrease in grain number per panicle.6. With regard to agronomic control methods, the effect of plowing and puddling was examined. Turn-over plowing in winter was effective to kill reproductive organs. Puddling was highly effective in killing both overwintering organs and shoots that have sprouted at the time of puddling, by burying them in the soil. Puddling combined with turn-over plowing in winter killed about 80% of the reproductive organs. In the fields of early season rice cultivation, plowing immediately after the rice harvest was also very effective in preventing tuber formation. In this case, rotary plowing was more effective than turn-over plowing.7. As for the herbicidal control, soil treatment after rice transplanting, foliage treatment with paraquat prior to puddling, and foliage treatment after rice harvest were analysed, and their suitability for effective control was evaluated.8. Based on the above results, an integrated control system for transplanted early-season rice cultivation was designed as shown in Fig. 9.

茎葉処理除草剤SL-236乳剤の大豆に対する薬害症状と生育収量への影響(年次講演会要旨)

茎葉処理除草剤SL-236乳剤の大豆に対する薬害症状と生育収量への影響(年次講演会要旨)