Pruning Date Research Articles

Pruning date and hydrogen cyanamide effects on growth and yield of grapevine var. Cabernet Sauvignon

Harvesting the grapes before the monsoon season is crucial to ensure the quality of berry and bunches. This study aims to identify the optimal window for pruning and hydrogen cyanamide (HC) application to prepone the berry harvesting. The experiment was conducted in randomized complete block design with five treatments and four replications. Treatments were five different pruning dates in 2021: Jan. 17, Jan. 24, Jan. 31, Feb. 7 and Feb. 14, followed by 5% HC application one week after pruning. Annual growth stages of grapevine were recorded by using modified E-L growth stage; reproductive attributes recorded during flowering; and vine yield and berry quality attributes recorded at harvesting. The earlier pruning resulted earlier budburst compared to late pruning. Vines prunefed after Feb. 7 had <50% budburst, while vines pruned before Feb. 7 reached 50% budburst, exhibiting no differences in number of days needed to achieve it. Jan. 17 pruning had the highest budburst (%) and bud fruitfulness (%), where pruning on Feb. 7 had lower values. Average bunch weight did not differ while berry quality attributes differed between treatments for the same day harvest. The negative responses in late pruned and HC treated vines, potentially attributed to the phytotoxic effect of HC on tender buds near the natural time of dormancy break. The early pruning and subsequent application of HC triggered earlier budburst, and advances flowering and harvesting of berries in grapevine. This research demonstrated a potential techniques for advancing harvesting time (2-3 weeks) in grapevine.

Long-Term Study of the Crop Forcing Technique on cv. Tempranillo (Vitis vinifera L.) Vines and Suggested Irrigation Strategies to Improve Water Use Efficiency of Forced Vines

Recently, the crop forcing technique (summer pruning that “forces” the vine to start a new cycle) has proven to be effective in delaying the harvest date and increasing must acidity, but also reducing the yield. However, recent information on deficit irrigation strategies combined with the crop forcing technique reveals that the crop forcing technique reduces irrigation water use efficiency. Two experiments were conducted. Experiment 1 was a 4-year trial to test the effect of the forcing pruning date on the phenology, yield, yield components and water requirements when post-veraison water stress is applied. In this experiment, the treatments were unforced vines (UF-RDI) and forced vines with a forcing pruning date about 70 (F1-RDI) and 100 (F2-RDI) days after budburst. The harvest date was delayed 34 (F1) and 66 (F2) days increasing the must acidity and malic acid concentration in the forced treatments. However, both forced treatments had a reduced yield (36% in F1 and 49% in F2) and irrigation water use efficiency (12% in F1 and 65% in F2). Experiment 2 was a 2-year trial in which irrigation was suppressed before the forcing pruning in F1 (F1-Pre) and F2 (F2-Pre) and after veraison. The yield, yield components, must quality and irrigation were compared to forced vines with irrigation suppression only after veraison (F1-RDI and F2-RDI). For the entire experiment, both treatments in which irrigation was suppressed before the forcing pruning reduced the amount of irrigation supplied (10% in F1-Pre and 30% in F2-Pre) with no negative effects on the yield, yield components or must quality when compared to F-RDI treatments.

Pruning and Training Systems Impact Yield and Cold Hardiness of ‘Marion’ Trailing Blackberry

The floricane-fruiting, trailing blackberry (Rubus L. subgenus Rubus, Watson) cultivar Marion was evaluated in two plantings for the impact of floricane pruning date. This included leaving the dead canes unpruned and training new primocanes over the dead wood (new-over-old), primocane topping and suppression date in alternate year (AY) and every year (EY) production systems at various planting densities. The presence of primocanes during fruit development did not affect yield of the floricane in the current season but suppressing primocanes to June 30 in Oregon, USA, led to insufficient time for primocane growth, reducing yield of the floricane the following year by 36% relative to no primocane suppression. Pruning out senescing floricanes immediately after fruit harvest or later—thus allowing more time for remobilization of nutrients or reserves—had no impact on yield. However, yield in the new-over-old system was higher, likely due to less training damage to primocanes in this treatment. All of the AY treatments studied led to lower berry weight compared to EY production but this has not been an issue in the processed fruit market to date. Plants in AY production produced more canes per plant than in EY but at the industry standard spacing of 1.5 m, AY plants yielded only 60% to 66% more than EY plants in these studies, despite evidence of plants in AY production having greater cold hardiness. There was no significant effect of planting at higher density (0.6 and 0.9 m) on cumulative yield over 4 years. However, planting at 0.6 m and topping the primocanes to the top trellis wire (1.8 m) increased yield significantly compared to other AY treatments. This alternative production system may offer economic advantages to the 1.5 m EY or AY production systems through reducing management costs and allowing for mechanical pruning and training.

Abscisic acid treatment to avoid late spring frosts damage during ‘Chardonnay’ vines budbreak

The production of early budbreak Vitis vinifera L. cultivars in southern Brazilian highlands has been limited by the occurrence of late spring frosts. This study aimed to evaluate the abscisic acid (ABA) application on different dates to delay 'Chardonnay' vines budbreak, avoiding periods of greatest probability of frost occurrence. Experiments were carried out in a commercial vineyard, in Sao Joaquim, Santa Catarina, Brazil, at 1,270 m a.s.l., 1,270 m altitude, 28°14'51”S, 49°57'42”W, in two cycles. Five ABA concentrations were adopted on each cycle, ranging from 0 to 2000 mg L-1 and applications were made on the traditional date of pruning, which in this area represents the time when budbreak starts on shoots' apical buds, and two anticipated dates up to thirty days from this last. ABA was incorporated into lanolin and the resulting ointment was applied on the top of pruned shoots. On 2012/2013 cycle, vines treated 22 days before traditional date of pruning (DBP) sprouted in 29 days after treatment (DAT), while those treated on traditional pruning date sprouted in 18 DAT. The maximum delay observed with ABA comparing to control was four days. Treatments applied 30 DBP on 2013/2014 cycle resulted in sprouting in 37 DAT, while treatments applied on traditional pruning date, in 15 DAT. Control vines sprouted in 25 DAT and those treated with 2000 mg L-1 ABA in 28 DAT, delaying budbreak by three days. The latest pruning date and the highest ABA concentration (2000 mg L-1) presented better effect on vine budbreak delay. Changes were in general more expressively caused by the change in application dates. There were no problems with non-broken buds and the production was only slightly changed by ABA treatments. ABA application through this methodology was little effective on delaying grapevines budbreak and is not recommended for commercial use.

Effect of Harvest Time and Pruning Date on Aroma Characteristics of Hop Teas and Related Compounds of Saaz Hops

Hops are requisite materials that impart bitterness, hoppy aroma, and flavor to beer. The purpose of this study was to understand the effect of harvest time and pruning date on aroma characteristics of beer for Saaz hops from the Czech Republic using quantitative descriptive analysis and two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC/TOF-MS) measurements. Hop teas were used for an alternative simplified sensory test to estimate the hop aroma profiles in beer. The key compounds in hops that are responsible for changes in hop aroma with harvest time and pruning date were quantitated with GC×GC/TOF-MS and multivariate analyses. Scores for aroma characteristics, such as floral, fruity, and citrusy characteristics, significantly increased for later harvest times and middle pruning dates. Additionally, the contents of certain compounds, such as Z-citral, linalool, and heptatonic acid, were positively correlated with the intensities of floral, fruity, and citrusy characteristics, whereas E-3-hexen-1-ol and octanoic acid were negatively correlated with these characteristics. The contents of these compounds were positively or negatively correlated with harvest time and pruning date. Therefore, the aroma profiles for hop teas or beer could be controlled by altering the harvest time and pruning date.

Postbudburst Spur Pruning Reduces Yield and Delays Fruit Sugar Accumulation in Sangiovese in Central Italy

The influence of pruning date on yield control and ripening rate of spur-pruned Sangiovese grapevines was investigated over two years (2013 and 2014). Winter pruning was applied on 1 or 4 Feb (mid dormancy); 1 or 5 March (late dormancy); 2 or 7 April (bud swell); 2 or 7 May (flowers closely pressed together); and 1 or 6 June (40 to 50% of flower caps fallen), respectively. Vine yield and fruit composition at harvest were not affected by shifting from the standard pruning dates of mid and late dormancy to the bud swell stage. In contrast, the number of inflorescences in compound buds was significantly reduced for vines pruned in early May. No inflorescences were retained on vines pruned at the beginning of June. Early May pruning reduced fruit set and berry weight and slowed fruit ripening compared to the other pruning dates. At harvest, must soluble solids and titratable acidity were 1.6 Brix lower and 1.8 g/L higher, respectively, for the May treatment compared to the standard pruning dates. The early May pruning dates also achieved higher total anthocyanins and phenolic concentrations than the standard pruning dates, indicating that this technique can potentially decouple the accumulation dynamics of these components. Further studies are needed to better calibrate winter pruning date for managing yield and berry maturation rate.

A non-destructive method based on digital image processing for calculate the vigor and the vegetative expression of vines

The vigor and the vegetative expression of vines are parameters of great interest in viticulture since they are indicative of the entire guidance system state. Traditionally these parameters are estimated and obtained using a destructive method by cutting the sticks, weighing them and finally obtain the medium weight of pruning sticks. This paper presents a non-destructive method that successfully determines the vine vigor based on a digital image processing. The method consists of acquiring a digital image of vines and applying a software to those images to determine vigor and vegetative expression. This application can be divided in two independent phases: the first one consists in a digital image processing, that isolate the vine sticks and determines the mean area per stick of the vine; the second one determines the vine vigor and vegetative expression based on a polynomial relationship between mean area and mean weight of stick. The software application was tested on thirty vines (Vitis vinifera cv. Touriga Nacional) characterized by low, medium and high vigor and selected during a three-year study. Since the mean weight of stick obtained using the mathematical expression and the values calculated using the real sticks present a 0.998 correlation, we can conclude that this new methodology successfully determines the vigor and the vegetative expression of vines. With this new methodology it is unnecessary determinate the pruning mass and the number of sticks per plant in the vineyard. It’s a simple use application that determines vigor and vegetative expression, based on a digital image of the vine and independent of the pruning date. This new method has a patent register in Portugal, with the reference number 105163.

Effects of summer pruning combined with winter pruning on bush growth, yields, and fruit quality of ‘Misty’ southern highbush blueberry for two years after planting

The effects of winter pruning severity and the date of summer pruning on growth, yields, and fruit quality of ‘Misty’ southern highbush blueberry were studied. The pruning treatments were as follows: 1) winter pruning severity [unpruned control, conventional pruning (30% removed), and severe pruning (50% removed)] and 2) winter pruning (conventional pruning) + summer pruning date (June 20, July 20, and August 20). The number of buds was highest (894.6) with conventional winter pruning (CWP) + summer pruning (SP) on July 20, followed by conventional pruning (CP) (784.4), then no pruning (NP) (712.2), severe winter pruning (SWP) (656), CWP + SP on June 20 (540), and finally CWP + SP on August 20 (333.4). In general, the improvement in light penetration to the canopy, shaping of bearing shoots, and strengthened cane were observed in the treatment of winter pruning combined with summer pruning on July 20. In the following year, total yields were highest with NP (1,648 g), followed by CWP + SP on July 20 (1,364 g), then CWP + SP on August 20 (962 g), CWP + SP on June 20 (859 g), SWP (844 g), and CWP (762 g). Fruit weight results were as follows: CWP + SP on June 20 (1.53 g) > SWP (1.50 g) > CWP + SP on August 20 (1.48 g) > CWP + SP on July 20 (1.44 g) > CWP (1.40 g) > NP (1.10 g), but there was no statistical difference between the fruit weight results except compared to no pruning treatment. Fruit (berries) were used to investigate SSC, TA, total sugar, firmness, total phenolic content, and anthocyanin content, and no significant differences were found among the treatments.

Development of Decision Support System for Protecting Distance between Power Lines and Trees

Resolving the contradiction between trees and power transmission lines in time is an important work to ensure the safety of transmission line operation. While it is difficult to decide the trees trimmed time during the transmission line operation and maintenance, the development of the management information system for protecting distance between transmission lines and trees, which is used to auxiliary predict the date of pruning, is a way to solve the problem. Collected attribute data of transmission lines and trees, the corresponding database is established. Therefore, Visual Basic 6.0 is adopted to develop the software system. Based on the spatial coordinates of line towers, conductors, and tree crown, the three-dimensional mathematical model is established to calculate the spatial distance between the conductor and tree crown. According to the mathematical model, the trees growth rate of year, month and day, respectively, and the protecting distance standard between conductor and tree crown, the system could calculate the actual spatial distance between conductor and tree crown, and auxiliary predict the pruning date.

Polynomial relation between mean shoot area and mean shoot weight for vigour calculation on cv. Touriga Nacional

<p style="text-align: justify;"><strong>Aim</strong>: To develop a new methodology for determining vine vigour based on a polynomial relation between mean shoot area and mean shoot weight.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Thirty grapevines (cv. Touriga Nacional) characterized by low, medium and high vigour were selected for a threeyear study. Vine vigour was determined each year by using the traditional “mean shoot weight” methodology. At the same time, the mean shoot area of each vine was determined by using digital image processing, where RGB images (Red Green Blue) were converted to HSV images (Hue Saturation Value) and then to binary images based on the saturation values with a threshold set to 0.15. Finally, we established a polynomial relation between mean shoot area and mean shoot weight, given by the equation <em>f(x)</em> = 0.0047<em>x</em><sup>2</sup> + 0.2254<em>x</em> + 0.0474, where <em>f(x)</em> corresponds to the mean shoot weight (vine vigour estimation) and <em>x</em> corresponds to the mean shoot area.</p><p style="text-align: justify;"><strong>Conclusions</strong>: The proposed method for calculating vine vigour based on a digital image of a vine and a polynomial relation between mean shoot area and mean shoot weight provides a highly reliable estimate of the actual vigour. Correlation for the 30 grapevines with three-year average of 99.8%.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: With this new methodology, it is unnecessary to determine the pruning weight and the number of shoots per plant in the vineyard. Its implementation is simple, based on a digital photography of the vine under study, and independent of the plot pruning date.</p>

Delimitação da aptidão agroclimática para videira sob irrigação no Nordeste Brasileiro

Dados climáticos médios foram usados em conjunto com modelos simples de regressão que relacionam o coeficiente de cultura (Kc), a evapotranspiração de referência (ET0) e os graus dias acumulados (GDac) para quantificar o requerimento hídrico de videiras (RHV) para mesa e para vinho no Nordeste brasileiro. O RHV juntamente com dados de precipitação permitiu o desenvolvimento de um índice hídrico para videiras (IHV), o qual foi aplicado com dados médios de temperatura do ar para os ciclos produtivos na caracterização de diferentes graus de aptidão sob irrigação, variando-se as datas de poda. Para produção de uvas de mesa constatou-se que não há limitação térmica na região, entretanto maiores teores de açúcar, bem como maior produção, podem ser obtidos nos locais com valores de temperatura do ar mais elevados. Com relação a videiras para vinho, ocorre alguma limitação térmica para a elaboração de vinhos de boa qualidade, dependendo da data de poda, com altos teores de álcool e baixa acidez obtidos nas condições de elevados valores de temperatura do ar. A melhor época de poda para videiras de mesa é de julho a setembro, destacando-se as áreas ao oeste dos estados da Bahia, Pernambuco, Paraíba e quase todas as áreas dos estados do Rio Grande do Norte, Ceará, Piauí e Maranhão. Considerando-se videiras para vinho o período com melhor aptidão climática é quando a poda é realizada entre maio e junho, destacando-se os estados da Bahia, Pernambuco, Paraíba, Alagoas, e Sergipe, e ainda a parte sudoeste do Estado do Maranhão.

Risco climático de ocorrência de doenças fúngicas na videira 'Niagara Rosada' na região do Polo Turístico do Circuito das Frutas do estado de São Paulo

O Polo Turístico do Circuito das Frutas do Estado de São Paulo congrega municípios produtores de uva comum de mesa, principalmente a cultivar "Niagara Rosada"�. Observa-se que no processo produtivo ocorre severa influência de doenças fúngicas foliares e seu controle chega a 30% do custo de produção. Nesse contexto, o objetivo foi determinar o risco climático (RC) de ocorrência das doenças fúngicas na 'Niagara Rosada' por meio da análise de séries históricas de dados pluviométricos diários para estimativa do número de pulverizações necessárias (NPchuva). O RC, assim como o NPchuva, foram calculados em cada época de poda, e para os diferentes municípios da região. A regionalização das áreas em função da necessidade de pulverização para controle de doenças fúngicas determinada pela ocorrência de chuvas, foi feita por meio de sistemas de informações geográficas (SIG) utilizando os valores médios de RC estimados, por equações de regressão linear, obtidas em função da altitude. Nas podas efetuadas em setembro, o RC foi mais elevado que nas de julho, sendo os valores mais elevados superiores a 70% e os menores, inferiores a 20% respectivamente.

The Stem Age Required for Floral Induction of Synchronized Mango Trees in the Tropics

The quantitative floral inductive role of the age of the last vegetative flush was investigated in replicated trials of two cultivars of mango (Mangifera indica L.), Keitt and Tommy Atkins, growing in tropical conditions of Cundinamarca State in Colombia. Empirical observations have indicated that stems must be in rest for sufficient time, generally 4 to 5 months, to be induced to flower in the absence of cool temperatures. Twelve trees per cultivar were tip-pruned to stimulate a synchronous flush of vegetative growth at the beginning of the experiments. The first of four sets, each consisting of three replicate trees among the 12, were sprayed with 4% potassium nitrate on a 2-week schedule beginning 2 months after the pruning date. Biweekly sprays continued in this first set until a growth response was observed, whereupon the set was retired from further observations, and the second set of three synchronized trees began receiving biweekly spray treatments until they initiated a growth flush. The schedule continued through the four successive sets of trees until the age of stems necessary to induce a flowering response was determined. Treatment applications were quantified using a one-m-square quadrate to determine the numbers of resting stems and vegetative and /or reproductive shoots contained within. KNO3 sprays applied 3 months after the pruning date stimulated initiation of vegetatively induced shoots in both ‘Keitt’ and ‘Tommy Atkins’ trees. Synchronous generative shoot initiation in ‘Keitt’ trees occurred in ≈75% and 100% of the stems after KNO3 sprays applied 5 and 6 months after the pruning date, respectively. Tommy Atkins, a cultivar that is more difficult to induce to flower than ‘Keitt’, had 18% of shoots flowering after the 5-month application and 100% flowering after the KNO3 application 6 months after the pruning date. None of the non-treated orchard trees flowered during this time. Stem age was the key factor correlated with flowering. The experimental trees, which were naturally habituated to experience two flowering periods per year, each within separate sections of tree canopy, were stimulated to produce one annual synchronized flowering event throughout the tree canopy as a result of the treatments.

EVALUATION OF THE CUTTING FORCE ON VINE BRANCHES IN WINTER PRUNING

Mechanical pruning, usually integrated with manual finishing, still excites some doubts regarding the quality of the cut which appears not to be the best as precision and cleanliness. This aspect, probably conditioned by the model and the application of pruning machines, might also be affected by the characteristics of the vine branches in particular by their cutting force. In order to evaluate the cutting force on different vine type, laboratory and field trails were carried out. The experiments were set in order to evaluate this parameter during winter pruning in relation to three variables: vine type; branch size; pruning time. The results show how the cutting resistance of vine branches during vegetative rest depends on vine variety (Trebbiano 675 N Cabernet 1175 N), on the diameter of the canes (increase of force from 56 % to 86 % between the classes of diameter) and on the pruning date (26% decrease of the cutting force in the latest period for Trebbiano and Sangiovese, and 32 % for Cabernet Sauvignon). Such variations, which can be considerable, affect directly the pruning results. High values of cutting force can generate tiring of operator in manual pruning or cutting damages on the vegetation during mechanical pruning.

Dry Matter Partitioning, Carbohydrate Composition, Protein Reserves, and Fruiting in ‘Autumn Bliss’ Red Raspberry Vary in Response to Pruning Date and Cane Density

In a 2-year experiment (1994 and 1995), plants of primocane-fruiting red raspberry cultivar ‘Autumn Bliss’ grown in a plastic greenhouse were destructively harvested at different growth stages to determine the effect of pruning date and cane density on dry matter distribution, carbohydrate concentration, and soluble protein concentration in different plant parts. Three summer-pruning dates (early, mid, and late July) and four cane densities (8, 16, 24, and 32 canes/m row) were imposed. Relative root biomass decreased from pruning to first flower stage and remained constant thereafter for all pruning dates. Earlier pruning dates corresponded to earlier fruit production, but yield was significantly reduced on later pruning dates and higher cane densities. Sucrose concentration was higher in fine roots than in suberized roots and had a slight decrease during flowering and the beginning of harvest. Soluble protein concentrations did not differ significantly between pruning dates. Reserve carbohydrates in the root system were unaffected by pruning and cane density, and were rapidly used during active vegetative growth, began to recover just after bloom, and were fully recovered at the end of the season. Our experiment suggested that in red raspberry plants grown under poor environmental conditions, current yield is reduced but there is enough carbohydrate accumulation to support next year's growth.

Comportamento fenológico de videira, cultivar Patrícia em diferentes épocas de poda de frutificação em Goiás

O experimento foi desenvolvido no município de Silvânia (GO), em pomar comercial de uva `Patrícia' (IAC 871 - 41) durante o período de fevereiro a outubro de 2003. O objetivo deste trabalho foi avaliar o comportamento fenológico e as características dos cachos e das bagas da cv. Patrícia em diferentes épocas de poda (13/3, 28/3, 12/4 e 27/4). A duração do ciclo (poda - colheita) foi de 152, 172, 185 e 178 dias para as podas realizadas em 13/3, 28/3, 12/4 e 27/4 respectivamente. As épocas de podas não afetaram significativamente o tamanho e a forma dos cachos, entretanto, grandes e medianamente compactos com comprimento médio de 20,52 cm. O maior diâmetro de baga foi encontrado na poda realizada em 27/4 com 19,14 mm, padrões considerados adequados para a cultivar. As diferentes épocas de poda não exerceram influência sobre os teores de sólidos solúveis totais, com média de 18,4 ºBrix. Todavia, houve variação significativa para a acidez total titulável, evidenciada nas podas de 13/3 e 27/4, respectivamente, com 1,44 e 0,87g de ácido tartárico/100 mL de mosto de uva. As diferentes épocas de poda afetaram significativamente a relação SST/ATT, sendo a menor relação encontrada na poda realizada em 13/3 com apenas 13,0 e a maior na poda de 27/4 com 21,9.

The timing of flush development affects the flowering of avocado (Persea americana) and macadamia (Macadamia integrifolia × tetraphylla)

Orchard trees of A4 macadamia (Macadamia integrifolia × tetraphylla) and Hass avocado (Persea americana) were thinned and tip-pruned at different times to generate a range of trees with different stages of leafy flush development. The stagger in the start of the first flush following pruning was repeated in the start of subsequent flushes, so pruning was an effective means of changing the phase of the cycle of flush development. The difference in phase affected flowering. In macadamia, over 80% of the variance in flowering was explained by regression against pruning time. Flowering ranged from 0 to 43% of tip-pruned branches, with the most profuse flowering on flushes appearing in July. In avocado, over 45% of the variance in flowering of the first flush following pruning, and over 35% of the second flush, was explained by regression against pruning time, with more flowering on those flushes starting nearer to the winter solstice. The control trees flowered better than the pruned trees but there was too little information to explain the difference. The macadamia control trees had less synchronised flushing than the pruned trees, and were not subject to internal thinning. The avocado control trees appeared to have a phase of flush development different from the pruned trees, with a summer flush commencing before the first pruning date and maturing before the maturation of the first post-pruning flushes. More research is needed for related canopy management guidelines.

Pruning Date and Cane Density Affect Primocane Development and Yield of `Autumn Bliss' Red Raspberry

The aim of this study was to determine the effects of date of summer pruning and cane densities on growth and fruiting characteristics of the raspberry (Rubus idaeus) plant. Three summer-pruning dates (early, middle, and late July) and four cane densities (8, 16, 24, and 32 canes/m row) were imposed to the greenhouse-grown primocane-fruiting raspberry `Autumn Bliss' in 2 consecutive years (1994 and 1995). A higher light microclimate and CO2 assimilation rate were measured within the canopy at the lowest density. Some compensation in CO2 assimilation rates were observed in the upper leaves of the high-density treatments, probably in response to low light. Delayed pruning decreased yield per cane and per row. The highest yields per cane were always observed at the lowest cane density. Densities of 16 and 24 canes/m produced the highest fruit yield. Light conditions appeared to be the most important environmental factor affecting plant productivity. Fruit were a weaker sink than roots; therefore, the role of carbohydrate reserves should be investigated.

Caracterização fenológica e requerimentos térmicos de variedades de uvas sem sementes no Vale do São Francisco

O comportamento fenológico e requerimentos térmicos de variedades de uvas sem sementes foram estudados nas condições do Vale do São Francisco durante os anos de 2001-2002, em seis diferentes datas de poda (12/2000, 04/2001, 06/2001, 10/2001, 01-02/2002 e 04/2002). O experimento foi realizado no Campo Experimental de Bebedouro, em Petrolina-PE. As variedades utilizadas foram Superior Seedless (Festival), Thompson Seedless, Catalunha, Perlette e Marroo Seedless, enxertadas sobre porta-enxerto IAC 572 ('Jales'). Avaliou-se a duração em dias dos estádios fenológicos, gemas dormentes (data de poda) a gemas inchadas (1), gemas inchadas a início de brotação (2), início de brotação a 5-6 folhas separadas (3), 5-6 folhas separadas a início de floração (4), início de floração à plena-floração (5), plena-floração a "chumbinho" (6), "chumbinho" à "ervilha" (7), "ervilha" a ½ baga (8), ½ baga a início de maturação (9) e início de maturação à maturação plena (10). Os requerimentos térmicos foram obtidos em termos de graus-dia (GD) necessários para atingir cada fase fenológica a partir da poda. O ciclo fenológico médio variou de 89 dias e 1.315 GD na variedade Superior Seedless a 105 dias e 1.514 GD na variedade Perlette, destacando-se as variedades Superior Seedless e Marroo Seedless como precoces e as demais com ciclo intermediário. Os períodos compreendidos entre o início e final da maturação, ½ baga a início de maturação e 5 a 6 folhas separadas a início de floração apresentaram a maior duração entre todos os subperíodos em todas as variedades.

Preliminary studies on the biology of Phaeoacremonium

Comparative microflora studies of one-year-old pruned and unpruned canes carried out during dormancy period over three consecutive years showed that Phaeoacremonium chlamydosporum was more frequently isolated from pruned than unpruned canes, while Phaeoacremonium aleophilum was found as much in pruned as in unpruned canes. Inoculations of pruning wounds made in two consecutive winters by suspensions of conidia of P. chlamydosporum and P. aleophilum showed that both fungi were able to invade through wounds during winter. Infections varied with pruning date and age of pruning wound, but were more serious and of longer duration with early pruning (December, January). Trapping studies showed that spores of P. chlamydosporum were captured throughout the whole year, while spores of P. aleophilum were mostly trapped during the vegetative period. Microscopic examination of adhesive tape applied to without bark zones of the canes showed the presence of conidia of P. aleophilum. From these studies, it emerged that only P. chlamydosporum is able to contaminate pruning wounds during winter. P. chlamydosporum and P. aleophilum may be propagated by infected canes in the nursery. They can be considered airborne fungi during a period of their biological cycle.