Early Defoliation Research Articles

Changes of Phenolic Contents and Antioxidant Activity in Soybean Seeds Harvested from Phakopsora pachyrhizi Infected Crops

Asian soybean rust caused by Phakopsora pachyrhizi is one of the most destructive foliar diseases on soybean. Severe infection of this disease causes early defoliation and reduces the yield. To determine the response of soybean genotypes to this disease and the changes of metabolites in seeds, a greenhouse study was conducted using eight Indonesian soybean cultivars, i.e. Malabar, Wilis, Ringgit, Pangrango, Argomulyo, Grobogan, Dena 1, and Dena 2. The experiment was arranged in a randomized completely block design and repeated three times. The soybean crops were inoculated with the pathogen and another set was not inoculated. Infection of P. pachyrhizi reduced fresh biomass, seed weight per plant, and weight of 100 seeds. However, total flavonoid contents in seeds increased from 12 to 50% in all infected genotypes. The increase of daidzein from 27 to 67% in seeds was observed, except for Malabar and Argomulyo . The increase of genistein was genotypic dependence. The increase of total phenolic contents as well as antioxidant activity was also depending on the genotypes. P. pachyrhizi could be one of the biotic elicitors to increase total flavonoid contents in soybean seeds. Dena 1 less suffered from the rust infection as represented by the least pustule number, less reduction in seed weight and weight of 100 seeds. Secondary metabolites particularly phenolics and isoflavones in seeds of this cultivar increased significantly after the rust infection. This cultivar could be considered as an alternative tolerant genotype where cultivated area is favorable for soybean rust infection.

Pathogenicity and taxonomy of Tenuignomonia styracis gen. et sp. nov., a new monotypic genus of Gnomoniaceae on Styrax obassia in Japan

Abstract Since 2010, an unknown fungus in the Gnomoniaceae has been found on overwintered leaves and petioles of Styrax obassia (Styracaceae) in Japan. This fungus is characterized by dark brown immersed or partially erumpent ascomata with long necks and fusiform to obovoid asci each with an acute or long tapering stipe. Each ascus bears eight fusiform to filiform ascospores. Our morphological observation and phylogenetic analyses based on the markers LSU, rpb2, and tef-1α indicated that this is a new monotypic genus in the Gnomoniaceae (Diaporthales), and Tenuignomonia styracis gen. et sp. nov. was descried herein. Members of the Gnomoniaceae are commonly isolated as endophytes, saprobes, and plant pathogens from a broad diversity of herbaceous, shade tree, and agriculturally significant plants. We thus carried out a pathogenicity test to determine if T. styracis is the causative agent of leaf blotch on S. obassia. One week after inoculation, this fungus produced small necrotic spots on the leaves and petioles, and all leaves having necrotic spots were abscised in a short time. We thus confirmed that this fungus has weak pathogenicity on S. obassia. This new species may promote early defoliation of S. obassia during the fall.

Intensity and timing of defoliation on white cultivar Chasselas under the temperate climate of Switzerland

Aim: The objective of this work is to investigate the effects of early defoliation on cv. Chasselas under the temperate conditions of Switzerland, with particular attention to berry anatomical traits and wine sensory parameters.Methods and results: Defoliation (removal of 6 basal leaves + 6 lateral shoots per shoot) was completed during three developmental stages of grapevine, i.e., pre-flowering, late flowering and bunch closure, and at two intensity levels. The experimentation was performed repeatedly over four years. In addition to vintage effect, pre-flowering defoliation had a consistent impact on vine agronomic behaviour. The yield was highly affected by the technique (more than 30% loss). Earlier and more intense defoliation had more impact on yield, while post-berry-set defoliation had no effect on yield. Intensive defoliation also modified berry skin thickness and had a positive impact inhibiting Botrytis development. Wine composition and sensory analysis were not affected by the practice. However, pre-floral defoliation affected bud fruitfulness and vigour, i.e., trimming and pruning weights. This result noted a carryover effect that could affect vine sustainability under restrictive conditions.Conclusion: In the context of this study, pre-flowering defoliation seems to be an interesting practice to reduce vigour and control the high production potential of the cv. Chasselas. The intensity of early defoliation allows for the modulation of the impact on the yield in order to prevent excessive yield loss.Significance and impact of the study: Pre-flowering defoliation of the white cultivar represents a prophylactic solution to reduce both chemical entrants and bunch-thinning costs.

Effects of early leaf removal on volatile compounds concentrations in Cabernet Sauvignon wines from the Ilok vineyards

The aim of this two year study was to evaluate effects of basal leaf removal before blooming on volatile composition of Cabernet Sauvignon wines in the Ilok vineyards (eastern Croatia). During two consecutive vintages (2013, 2014), two different treatments of basal leaf removal were applied: removal of 3 and 6 leaves, and control without leaf removal. Volatile compounds of resulting wines were identified and quantified by gas chromatography coupled with mass spectrometry. Organic acids and higher alcohols remained unaffected by treatments of early defoliation wine, except acetic acid and 2-methyl-6-hepten-1-ol. Early leaf removal was affected on six esters concentration only in the 2014 with different outcome. For compounds unaffected by defoliation, vintage was statistically significant source of variability, as the results of multivariate analysis have confirmed. Defoliation treatments in Cabernet Sauvignon wines from eastern continental part of Croatia should be adjusted to the weather condition in growing season.

Seasonal progression of leaf rust in ‘Niagara Rosada’ grapevine in a biannual crop system in Brazil

Grapevine leaf rust, which is caused by the fungus Phakopsora euvitis, is an important late-season disease of ‘Niagara Rosada’ (Vitis labrusca) grapevine in Brazil. The early defoliation of plants caused by the disease impairs fruit ripening and reduces marketable yield. In a study carried out in northern Parana State, the temporal progression of grapevine leaf rust was quantified in a production system of ‘Niagara Rosada’ grapevine with two growing seasons per year: mid-summer-autumn and late winter-spring. The influence of weather-related variables on rust progression was examined through correlation analyses. It was observed that the rust was more severe in summer-autumn than in winter-spring. Significant positive linear correlations (P ≤ 0.05) were found between rust severity and rainfall (r ≥ 0.90) and average daily hours of leaf wetness (r ≥ 0.82). In addition, negative correlation was found between rust severity and temperature (r ≥ −0.84) in the mid-summer/autumn season. Mild temperatures in autumn were considered decisive for rust progression. In Brazilian tropical viticulture, management strategies for grapevine leaf rust must consider the risk of rust damage in autumn caused by temperature.

First Report of Powdery Mildew Caused by Podosphaera xanthii on Ricinus communis in Korea

Ricinus communis L. (Euphorbiaceae), known as castor bean, is widely planted in the tropical and warm temperate areas. The seed is a source of castor oil, which has plenty of applications in medicine and as a motor lubricant (Worbs et al. 2011). In September 2016, powdery mildew symptoms were observed on several castor bean plants grown as a leafy vegetable in a private garden in Gimcheon (36°07′09″N, 128°07′46″E), Korea. White patches consisting of hyphae, conidiophores, and conidia were distributed on both sides of leaves. Infections were weak and did not cause early defoliation or leaf distortion. A representative specimen was deposited in Korea University Herbarium (KUS-F29541). Hyphal appressoria were nipple shaped. Conidiophores were erect, 110 to 230 × 10 to 12 μm, and produced two to five immature conidia in chains. Foot cells of conidiophores were cylindrical, 40 to 70 μm, and somewhat constricted at the basal parts. Conidia were ellipsoid to ovoid, 28 to 35 × 16 to 19 μm with a length/width ratio of 1.6 to 2.2, and contained distinct fibrosin bodies. Germ tubes produced from the lateral position of conidia were simple to forked. Primary conidia were apically conical or rounded, mostly subtruncate at the base, and generally smaller than secondary conidia. No chasmothecia were observed during the growing season. These structures are typical of the powdery mildew Fibroidium anamorph of the genus Podosphaera (Braun and Cook 2012). The internal transcribed spacer (ITS) regions of the specimen KUS-F29541 were amplified and sequenced with primers PMITS1/PMITS2 (Cunnington et al. 2003). The ITS sequence was deposited in GenBank (accession no. MG462908). It showed over 99% similarity with Podosphaera xanthii sequences obtained from Cucurbita pepo (KJ698669), Calendula officinalis (AB525914), and Verbena brasiliensis (KJ472787). Based on the morphological characteristics and molecular data, the fungus on R. communis was identified as P. xanthii (Castagne) U. Braun & Shishkoff (Braun and Cook 2012). Inoculation tests were conducted by pressing infected leaves onto 12 healthy leaves of three castor bean plants. Three noninoculated plants were used as controls. These plants were kept in a greenhouse at 24 to 30°C without artificial illumination. Typical powdery mildew symptoms developed on the inoculated plants after 5 days; however, the controls remained symptomless. The morphological characteristics of the pathogen on inoculated plants were in agreement with those on the diseased plants observed originally. There have been many records of powdery mildews belonging to Golovinomyces, Leveillula, Oidium, and Ovulariopsis on R. communis (Farr and Rossman 2017). However, no previous record of Podosphaera on R. communis has been found. To our knowledge, this is the first report of P. xanthii on R. communis globally as well as in Korea. Although identified from one locality, the natural occurrence of powdery mildew would be a new threat to this economically important crop in Korea.

First Report of Phytophthora cinnamomi Causing Trunk Canker of Almond in California

Almond (Prunus dulcis) is the most economically important nut crop in California, accounting for $5.9 billion value in 2016. During fall of 2015, declining 2-year-old almond trees on clonal Hansen 536 (peach × almond) rootstock were observed in a commercial orchard in Kern County, California. Affected trees expressed early defoliation with amber-colored gummosis on the trunk. Cankers developed at the bud union and extended into the scion in trees planted with their bud union placed at or below the soil surface. To isolate the causal agent, necrotic pieces of bark and subtending vascular tissue were cut from the canker margin, surface sterilized in 0.5% sodium hypochlorite solution for 3 min, rinsed twice in sterile water, and plated on corn meal agar amended with selective antibiotics (PARP) (Jeffers and Martin 1986). After several days of incubation at 25°C, Phytophthora-like colonies grew from the diseased tissues and were transferred onto acidified potato dextrose agar medium (APDA). The isolates were tentatively identified as Phytophthora cinnamomi Rands based on morphological characteristics. Sporangia were nonpapillate and ovoid to obpyriform or ellipsoidal to elongate-ellipsoid with an apical thickening, avg. 57.2 × 36.6 µm with a length-width ratio of 1.56; mycelium with abundant coralloid hyphal swellings. Globose chlamydospores formed abundantly in culture on the parent hyphae or on new hyphal branches (18 to 42 [avg. 27.65] μm in diameter) (Erwin and Ribeiro 1996). For all isolates, the internal transcribed spacer (ITS) regions of the rRNA gene and a portion of the β-tubulin (TUB) gene were amplified and sequenced with primers ITS1/ITS4 and TUBUF2/TUBUR1 (Lan et al. 2016), respectively. Two representative sequences for each locus were deposited in GenBank (ITS; KY924650 and KY924651, TUB; KY924648 and KY924649). BLASTn analysis against Phytophthora Database (www.phytophthoradb.org) showed that the ITS sequences had 99% identity and the β-tubulin sequences had 97 to 98% identity to reference sequences of P. cinnamomi (ITS: GU259227; TUB: EU079894). Two of the almond isolates of P. cinnamomi were tested for pathogenicity by wound inoculating 2-year-old potted almond trees of cv. Nonpareil on rootstocks of Hansen 536 and Nemaguard (Prunus persica × Prunus davidiana). Five-millimeter-diameter mycelial disks from PDA cultures of each isolate (and sterile PDA as a control) were used for inoculating wounds of the same size (5 mm) made in stems of: i) the almond scion on Hansen 536 rootstock, ii) the almond scion on Nemaguard rootstock, iii) Hansen 536 rootstock below the scion, and iv) Nemaguard rootstock below the scion. Five replicate trees were inoculated per combination of the three inoculants (two of P. cinnamomi, one control) and the four inoculation treatments in a randomized complete block design. After inoculation, the wounds were covered with petroleum jelly and wrapped with Parafilm. Two months after inoculation, all plants inoculated with the control remained healthy, whereas all scions and rootstocks inoculated with either isolate developed stem cankers. None of the trees inoculated on the rootstocks died during the experiment, but 40% of the trees inoculated on the scion were killed. P. cinnamomi was reisolated only from the infected plants. More than 10 other species of Phytophthora were reported to cause root and crown rots as well as aerial cankers on almond (Browne and Viveros 1999; Browne et al. 2015). To our knowledge, this is the first report of P. cinnamomi causing trunk canker disease of almond in California.

Changes in Photosynthesis and Carbohydrate Reserves of ‘Fuji’/M9 Apple trees in Response to Early Defoliation at Growing Period

Changes in Photosynthesis and Carbohydrate Reserves of ‘Fuji’/M9 Apple trees in Response to Early Defoliation at Growing Period

Tolerance of Faba Bean Plants (Vicia faba) to Partial Defoliation

Throughout the development of plants, certain biotic and abiotic phenomena can occur which reduce not only the photosynthetic area, but also the growth, depending on the stage of plant development. Responses by plants to defoliation depend on species, the timing of agricultural practices and the intensity level of defoliation. An experiment was carried out in Tunja, Colombia under greenhouse conditions, in order to evaluate the tolerance of faba bean plants (Vicia faba) to partial defoliation. Every week material was removed along each newly emerged leaflet to simulate 50% defoliation. Another group was grown with the entire leaf area to function as a control. As a result of partial defoliation, the specific leaf area, absolute growth rate, relative growth rate and total biomass were reduced, but the leaf weight ratio was increased. In addition, the pattern of dry matter partitioning was altered so that the amount of biomass accumulated was reduced in the roots, but increased in the leaves. Additionally, the partially defoliated plants showed the ability to partly restore the removed leaf area. In this way it could be inferred that the plants of Vicia faba present a moderate capacity to tolerate early defoliation during the vegetative phase.

Herbaceous vegetation response to controlled fire and postfire defoliation in a semiarid rangeland of Argentina

ABSTRACTSemiarid rangelands of central Argentina are shaped by fire and grazing. The aim of this study was to quantify the effect of controlled fire on aboveground biomass production of (1) herbaceous species as a whole group and (2) herbaceous species subclassified as desirable or undesirable perennial grasses and as herbaceous forbs at the end of two growing seasons after an experimental fire in a semiarid rangeland of central Argentina. The effect of the length of the resting period after fire on aboveground biomass production of desirable perennial grass species was also assessed; treatments consisted in defoliations at the end of the first and second postfire growing seasons, at the beginning and at the end of the second postfire growing season and only at the end of the second postfire growing season. Total biomass production of the burned treatments was higher than that of the control treatment, the difference being attributed to an increase in desirable perennial grass species biomass. This in turn was negatively affected by defoliation at the end of the first postfire growing season, suggesting that the beneficial effect of fire on biomass production might have been overridden by the stress imposed by an early defoliation. Overall, the results of the present study suggest that grazing should be held back for at least a whole year after the fire to achieve the pursued aim of increasing forage production by the use of controlled fire.

Comparison of the Effects of Early and Conventional Defoliation on Fruit Growth, Quality and Skin Color Development in ‘Fuji’ Apples

We compared the quality of ‘Fuji’ apples (Malus × domestica ) from trees whose leaves were not removed (no artificial defoliation; NAD) with apples from trees that underwent early defoliation (ED, treated in mid September and early October) and conventional defoliation (CD, treated in early and mid October). The experiment was conducted in three consecutive years using 15-year-old ‘Fuji’ apple grafted on Malus prunifolia . Fruits were harvested on November 7, 16 or 12 in 2011, 2012 and 2013, respectively. Compared to NAD treatment, ED and CD treatment reduced the fresh weight by 4.7% and 0.6%, respectively. The soluble solids content of NAD apples (14.4°Brix) was slightly higher than that of CD (14.1°Brix) and ED (14.0°Brix) apples. Soluble sugar content, flesh firmness, water-core index, and titratable acidity were not affected by defoliation treatment regardless of treatment timing. The skin blush index of NAD apples (2.3) was inferior to that of CD (3.3) and ED (3.4)- treated apples. Furthermore, artificial defoliation treatments increased skin redness (a*) and yellowness (b*) and significantly improved the degree of skin blush compared to NAD fruits.

Influence of timing and intensity of fruit zone leaf removal and kaolin applications on bunch rot control and quality improvement of Sauvignon blanc grapes, and wines, in a temperate humid climate

Leaf removal is beginning to receive consideration for many growers as an important cultural practice for bunch rots control. It is normally applied after veraison and almost only on red varieties because of the high sunburn susceptibility of white grapes varieties under Uruguayan climatic conditions. The aim of this study was to determine the time and intensity of leaves removal impact on bunch rots and grapes quality on Sauvignon blanc. In parallel, the effects of kaolin (Surround® WP) applications in reducing the negative impact of excessive exposure to high temperatures were evaluated. Different intensities and times of defoliation, in combination with kaolin applications, were evaluated over 2006/07, 2007/08 and 2008/09 seasons. All defoliation treatments and mainly those made after fruit set, significantly reduced the occurrence of bunch rots, having a critical impact on those metabolites responsible for the final taste of wines. Early defoliation was significantly more effective controlling Botrytis incidence and improving berry quality than later in the season. Leaf removal had a determining impact over fruit quality and primary and secondary metabolites contents. An increase in soluble solids and glycosides concentrations was observed, while IBMP grape content was reduced, thus affecting the flavor of Sauvignon blanc wines. Kaolin applications significantly reduced berries temperature, sunburn and other berry damages associated with clusters solar exposure.In sum, leaves removal and exogenous kaolin application in Sauvignon blanc showed great potential as Botrytis mitigation strategy because it positively impacts berry quality as a result of many molecular and biochemical changes in key secondary metabolic pathways. Simultaneously reducing berry sunburn.

Effects of early leaf removal on grape yield, chemical characteristics, and antioxidant activity of grape variety Cabernet Sauvignon and wine from eastern Croatia

ABSTRACTThe aim of this study was to determine the impact of two different treatments of early defoliation performed before blooming on: grape yield, chemical parameters, polyphenols content, and antioxidant activity of grape and red wine cv. Cabernet Sauvignon from the vineyard located in Ilok, the eastern continental region of Croatia. Two different treatments of leaf removal (LR) were performed: removal of 3 leafs (T1) and 6 leafs (T2) before blooming, together with control (no leaf removal) (T3) during two years (2013 and 2014). Crop yield and average cluster weights per vine were determined. Density, pH and titratable acidity were measured in must, while the total phenols, total anthocyanins and antioxidant activity were measured in the extract of grape skin and produced wine. The analysis of individual anthocyanins in wine was performed by HPLC method. T2 treatment significantly lowered the crop yield and the average cluster weights, and increased total phenols, total anthocyanins, antioxidant activity and most abundant individual anthocyanins in wine. Defoliation did not affect the other chemical parameters in must, grape skin extract and wine. Vintage year is statistically the most significant source of variability for density of must, antioxidant activity in grape skin extract, as well as pH and titratable acidity in wine. This study has showed that the early leaf removal treatment in eastern continental part of Croatia could be used for the production of smaller quantity of high quality Cabernet Sauvignon red wine abundant with anthocyanins.

Transcriptional Responses to Pre-flowering Leaf Defoliation in Grapevine Berry from Different Growing Sites, Years, and Genotypes.

Leaf removal is a grapevine canopy management technique widely used to modify the source–sink balance and/or microclimate around berry clusters to optimize fruit composition. In general, the removal of basal leaves before flowering reduces fruit set, hence achieving looser clusters, and improves grape composition since yield is generally curtailed more than proportionally to leaf area itself. Albeit responses to this practice seem quite consistent, overall vine performance is affected by genotype, environmental conditions, and severity of treatment. The physiological responses of grape varieties to defoliation practices have been widely investigated, and just recently a whole genome transcriptomic approach was exploited showing an extensive transcriptome rearrangement in berries defoliated before flowering. Nevertheless, the extent to which these transcriptomic reactions could be manifested by different genotypes and growing environments is entirely unexplored. To highlight general responses to defoliation vs. different locations, we analyzed the transcriptome of cv. Sangiovese berries sampled at four development stages from pre-flowering defoliated vines in two different geographical areas of Italy. We obtained and validated five markers of the early defoliation treatment in Sangiovese, an ATP-binding cassette transporter, an auxin response factor, a cinnamyl alcohol dehydrogenase, a flavonoid 3-O-glucosyltransferase and an indole-3-acetate beta-glucosyltransferase. Candidate molecular markers were also obtained in another three grapevine genotypes (Nero d’Avola, Ortrugo, and Ciliegiolo), subjected to the same level of selective pre-flowering defoliation (PFD) over two consecutive years in their different areas of cultivation. The flavonol synthase was identified as a marker in the pre-veraison phase, the jasmonate methyltransferase during the transition phase and the abscisic acid receptor PYL4 in the ripening phase. The characterization of transcriptome changes in Sangiovese berry after PFD highlights, on one hand, the stronger effect of environment than treatment on the whole berry transcriptome rearrangement during development and, on the other, expands existing knowledge of the main molecular and biochemical modifications occurring in defoliated vines. Moreover, the identification of candidate genes associated with PFD in different genotypes and environments provides new insights into the applicability and repeatability of this crop practice, as well as its possible agricultural and qualitative outcomes across genetic and environmental variability.

Phytophthora pluvialis Studies on Douglas-fir Require Swiss Needle Cast Suppression.

Phytophthora pluvialis is associated with early defoliation and shoot dieback in Douglas-fir in Oregon and New Zealand. In 2013, P. pluvialis was described from mixed tanoak-Douglas-fir forests in the Pacific Northwest and concurrently recognized as the main causal agent of red needle cast (RNC) in New Zealand radiata pine plantations. Little is known about its infection cycle and impact on host physiology. P. pluvialis studies in Douglas-fir are challenging due to the ubiquitous presence of the endophyte Phaeocryptopus gaeumannii, which produces similar symptoms and premature defoliation with persistent needle wetness, known as Swiss needle cast (SNC). Nonetheless, our study showed P. pluvialis infection in the presence of SNC. Exclusive expression of P. pluvialis is difficult to achieve as both diseases are promoted by high humidity. Here we established a 'dry leaf' strategy to suppress SNC when inoculating Douglas-fir needles for RNC studies. Sheltering plants along with drip irrigation to avoid needle wetness during the P. gaeumannii sporulation period suppressed its development in the new season flush. The diminished endophyte inoculum enabled bias-reduced studies of P. pluvialis impacts on Douglas-fir without the confounding effects of stomatal blockage and premature defoliation caused by P. gaeumannii.

Detection of Apple Marssonina Blotch Disease Using Particle Swarm Optimization

<abstract> <b><sc>Abstract.</sc></b> Apple Marssonina blotch (AMB) is a devastating disease that is predominantly found in Asian countries, such as Japan, India, and South Korea. The disease has been known to cause huge economic losses in the regions where it has been found. AMB causes early defoliation, which ultimately leads to low quality and quantity of harvested apples. In this work, spectroscopic measurements were collected and analyzed for two datasets from 2014 and 2015. A stochastic algorithm called particle swarm optimization (PSO) was used to find optimal features for classification. A total of ten spectral features were found by the algorithm by selecting pairs of bands that resulted in the highest discrimination between every two classes. A support vector machine classifier resulted in 100% classification accuracy for both healthy and diseased samples. Abundance estimation and spectral unmixing analyses of early-stage AMB (ambE) samples were also conducted using PSO to extract symptomatic and asymptomatic endmembers. Results showed reasonable separation between healthy, seemingly healthy, and symptomatic classes. Quantitative analysis, using varying degrees of infection of ambE samples, was performed by applying a combination of partial least squares and stepwise multiple linear regression models, and coefficients of determination (R²) of 0.76 and 0.71 were achieved for the calibration and validation datasets, respectively. The results demonstrate the potential of using spectroscopic technology as a non-invasive method for early detection of AMB disease.

Effects of early defoliation on the skin phenolic composition of ‘Tempranillo’ grapevines

Effects of early defoliation on the skin phenolic composition of ‘Tempranillo’ grapevines

Impact of Cluster Zone Leaf Removal on Grapes cv. Regent Polyphenol Content by the UPLC-PDA/MS Method.

Leaf removal is known to enhance light exposure of clusters and therefore may affect grape composition. Owing to the risk of decreasing grape quality or sunburn as a consequence of improper sun exposure, it is crucial to determine the optimum leaf removal techniques adequate for the particular climate conditions of a vineyard area. Defoliation experiments on vine cv. Regent were conducted in two consecutive years (2014 and 2015). The effect of leaf removal treatment on the qualitative and quantitative composition of the polyphenol compounds in the grapes, with reference to the basic weather conditions of the vineyard area, located in Szczecin in the North-Western part of Poland, was assessed. Defoliation was performed manually in the cluster zone at three phenological plant stages: pre-flowering, berry-set and véraison. Leaf removal, especially early defoliation (pre-flowering), enhanced total polyphenol content, including the amount of anthocyanins, flavonols and flavan-3-ols and furthermore, it increased the amount of soluble solids, decreasing the titratable acidity in grapes. On the other hand, the treatments had a reducing impact on the phenolic acids in berries. Defoliation at earlier stages of cluster development appears to be an efficient strategy for improving berry quality in cool climate areas, however, additionally further weather data control is required to determine the effects on berry components.

Ramularia leaf spot severity and effects on cotton leaf area and yield1

ABSTRACT Cotton monoculture favors the development of diseases such as ramularia leaf spot, which causes early defoliation and boll rotting, thus decreasing yield. This study aimed at evaluating the severity of ramularia leaf spot and its effects on cotton leaf area and yield. The experiment was conducted in a triple (4 x 3 x 2) factorial design, consisting of four cultivars (FM940GLT, FM944GL, TMG42WS and TMG43WS), three thirds of the plant (lower, middle and upper) and two management conditions (with and without fungicide application). To the variable area under the disease progress curve, the lowest values were observed in the upper third of the TMG42WS and TMG43WS cultivars, with the lower and middle thirds presenting the highest severity. The condition managed with fungicide and the upper third showed the lowest values for area under the disease progress curve. The leaf area was negatively affected by the ramularia leaf spot. Concerning the seed and fiber yields, the highest averages were observed for the middle third and the condition managed with fungicide. There was no statistical difference for cotton yield loss.

Early leaf removal applied in warm climatic conditions: Impact on Tempranillo wine volatiles

Defoliation is a cultural practice with demonstrated benefits in grape and wine quality. The objective of this study was to evaluate the effect of early leaf removal applied in warm climatic conditions on volatile composition of Tempranillo wines. During three consecutive vintages (2009–2011) wine volatile compounds (alcohols, C6-compounds, ethyl esters, acetates, volatile acids, lactones and carbonyl compounds) from defoliated and non-defoliated vines were identified and quantified by GC–MS. Early leaf removal induced the increase of the concentration of all families of volatile compound quantified with exception of lactones. Significant increase was observed for 23 out 34 volatile compounds analyzed. The vintage effect also was shown, where the highest effect of defoliation was exhibited in 2009 vintage. Principal component analysis (PCA) showed a good separation of defoliation, non-defoliation and vintage according to wine volatile composition. The analysis of odour activity value (OAV) exhibited an increase of fruity and floral odour on Tempranillo wines when early defoliation was applied.