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The aim of the study was to observe the occurrence and development of the leaf spot symptoms caused by Pseudomonas syringae pv. actinidiae (Psa) on kiwifruit during the growing season in order to determine both the climatic predisposing factors and plant susceptibility. The observation was carried out over the years 2013 and 2014 in naturally infected kiwi fruit orchards. Two kiwi fruit orchards of the ‘Hayward’, and three of the ‘Hayward’, ‘Erika Bo’, ‘Jin Tao’ were observed in 2013 and 2014 respectively. 15-20 shoots of 6 untreated plants were randomly chosen, marked and weekly observed from bud break until leaf fall, scoring the number of new leaves and the number of spots per leaf. In this way it was possible to know the age of the leaf at the onset of the first symptoms and the evolution of the symptoms on the leaves during the season. Weather data were also recorded so as determine the period in which the infection presumably took place. Results showed that, under the climatic conditions of Emilia Romagna, foliar symptoms seem to occur only in springtime and that from the first two weeks of June even newly formed leaves do not show new symptoms of the disease. Finally, the leaves with spots born in spring were randomly collected before their fall and analyzed. From such leaves PSA was always isolated. Therefore, bacterial leaf spots formed in spring remain active until autumn.

The average gradient heat-pulse method (CHMP-AG) has been used to monitor sap flow in very young (1-year-old) apple trees, from budburst through until leaf fall. Data are presented to illustrate how CHPM-AG can resolve the full range of sap flux densities in these small trees. The methodology has been implemented by making a very simple software change to existing CHPM instrumentation.

In Brazil, leaf abscission in apple trees can occur prematurely due to infection by Glomerella leaf spot (Colletotrichum gloeosporioides). The extent of leaf fall is correlated with ethylene production resulting from the reaction by the host to prevent the dissemination of the pathogen. The aim of this study was to verify the impact of the aminoethoxyivinylglycine (AVG) on the process of leaf abscission in plants exhibiting Glomerella leaf spot symptoms. The experiment was conducted in the spring of 2011 in ?Maxi Gala?/M9 young apple trees (2 years old) in pots under greenhouse conditions at 22±2°C, with 80±5% relative humidity, (28°30?52?S and 50°52?58?W, 950 m). Plants without disease symptoms were artificially inoculated with C. gloeosporioides, and treatments were applied when the leaves had symptoms of infection. The experiment included 7 treatments with AVG and/or the fungicide Folpet (mg L-1 active ingredient ? a.i.) as follows: AVG 60, AVG 150, AVG 30 + Folpet 120, AVG 45 + Folpet 120, AVG 60 + Folpet 120, AVG 150 + Folpet 120, Folpet 120 alone and the untreated control. Assessments of percentage defoliation were made weekly until 68 days after spraying (das). The results indicated that AVG in doses 60 and 150 mg L-1 resulted in a reduced level of defoliation, compared with the fungicide treated trees, and abscission was equivalent to control at 21 das. After the disease is established and is not controlled by fungicide there was an increase in leaf abscission compared to the control.

Effect of boron (B) application on vegetative growth, yield, and fruit quality and leaf mineral contents of ‘Le-Conte’ pear trees was studied under field conditions. Boron at 0, 200, 400 and 600 mg L-1 B/tree was applied as soil application three times (i) before bloom (BB) (at green and white bud stage and when 1-5% of flowers were at full bloom), (ii) after bloom (AB) on 15 June, (iii) after harvest (AH) (at approximately 6 weeks before leaf fall). Boron application reduced vegetative growth parameters (shoot length, % of increase in trunk circumference and trunk cross sectional area). Applying B after harvest resulted in the highest fruit set and fruit retention percentages, in addition to total yield. Fruit physical and chemical properties and leaf contents of N, P, K, Ca, Mg and B were improved due to B application. The recommended economic treatment is to apply B at 400 mg L-1 after harvest (AH).

The objective of this work was to determine the chilling and heat requirements of Persian walnut cultivars and genotypes using excised twigs. The experiment was carried out from November to March 2006 and 2007. One-year-old twigs were prepared from four cultivars and four domestic genotypes (Juglans regia L.). After leaf fall, the twigs were taken and placed in plastic bags and kept at 4±1°C to provide 400 to 1500 chilling hours. After chilling, the excised twigs were transferred to the greenhouse. The cultivar 'Serr' and 'Z 30 ' genotype had the lowest chilling requirements (650 hours). 'Lara', `Z 63 ', 'Z 53 ', 'Pedro' and 'Z 67 ' showed intermediate chilling requirements, with values of 900, 900, 800, 750 and 750 hours, respectively. Finally, 'Hartley' completed its dormancy after the accumulation of 1000 hours, being the walnut cultivar with the highest chilling requirement in our study. The cultivars and genotypes were classified into three groups based on their heat requirements: low requirement ('Z 30 ' and 'Serr'), medium requirement ('Z 53 ', 'Z 67 ', 'Lara' and 'Pedro') and high requirement ('Hartley' and `Z 63 ').

Preliminary results of coffee berry growth modeling at the branch level are presented. The model, RAMCAF, is based on an existing model developed for peach. Parameters such as light extinction within the coffee tree canopy and potential fruit and shoot growth rates were derived from an experiment conducted over a period of two years on dwarf arabica coffee trees in Costa Rica with varying fruit loads and contrasting light regimes. Equations of leaf fall versus time as well as net photosynthesis versus photosynthetically active radiation were also obtained from experimental data. Simulations illustrate over the production cycle the effects of fruit load, level of shade and plant water status on fruit growth and carbon partitioning between the vegetative and reproductive branch compartments. Future developments such as coupling RAMCAF with a 3-dimensional architectural model of coffee trees to improve calculation of light interception and carbon assimilation are proposed. (Resume d'auteur)