Immature Nuts Research Articles

Assessment of farmers’ knowledge on the foliar fertilizer use for improved cashew (Anacardium occidentale L) productivity in south-eastern Tanzania

Purposethe study aim was to evaluate the farmers' knowledge on fertilizer use in cashew by assessing their awareness on the fertilizers, extent of use, obtained benefits from use in cashew, limiting factors of use, availability and changes after use. Cashew (Anacardium occidentale L) is a recent topmost strategic crop in Tanzania. Through cashew, earnings of > $585 million were reached in 2017/18 season. Chlorosis, flower abortion and dropping of immature nuts hinder cashew production referring the decrease from 3200,000 Metric Tons (MT) in 2017/18 to less than 200,000 MT in 2021/2022. Farmers’ knowledge on fertilizer use in cashew is not precisely known. Methodsthrough cross-section design using questionnaires, purposive sampling of respondents was done. Four villages each from three agro-ecologies i. e, Makonde Plateau (MP), Tunduru Dissected Plains (TDP), and Masasi-Nachingwea Plains (MNP) were selected in South-eastern, Tanzania. About 480 households were interviewed. Resultsabout 75% of respondents were aware of foliage fertilizers while 45.4% agreed on their suitability for cashew. About 44.7%, 27.9%, and 27.4% of respondents use foliar fertilizers in TDP, MP, and MNP, respectively. Some respondents (3.7%) apply 1 L of foliage fertilizers per round acre−1 and 5.1% apply for 1–3 rounds, and some few (1%) apply up to 10 rounds season−1. Cashew farming experience and credit access negatively influenced foliar fertilizer uses; hence foliar fertilizer prices linearly reduced the extent of use. Conclusionlimited knowledge among the farmers on fertilizer use in cashew was a challenge. Therefore, farmers' training and detailed fertilizer use research are recommended.

Immature Nut Fall of Coconut and Incidence of Rugose Spiraling Whitefly <i>Aleurodicus rugioperculatus</i> Martin

Studies on the immature nut fall in Aleurodicus rugioperculatus Martin infested coconut palms with low (<10 spirals/ leaflet), medium (10-20 spirals/ leaflet) and high (> 20 spirals/ leaflet) incidence in Dr YSRHU- Godavari Ganga hybrid and local East Coast Tall (ECT) variety were undertaken at the Dr YSRHU- Horticultural Research Station (HRS), Ambajipeta and Kalavalapalli plantations. The overall dropped nuts (%) was 4.84, 27.48 and 35.32% at Ambajipeta, while it was 5.50, 28.11 and 36.01% in Godavari Ganga hybrid palms with low, medium and high incidence during 2020-21 at Kalavalapalli. The % of dropped nuts in ECT variety with low incidence, respectively was representing the general dropping with 4.06 and 4.68% at Ambajipeta and Kalavalapalli, respectively during 2020-21. In case of ECT palms with medium and high incidence, the nut dropping was 22.33 and 28.51% (Ambajipeta), and 23.49 and 30.58% (Kalavalapalli).

Diaporthe and Diplodia Species Associated with Walnut (Juglans regia L.) in Hungarian Orchards

Walnut (Juglans regia L.) production is a developing sector in Hungarian horticulture, where preharvest fruit rot increasingly causes economic losses. Previously, fungi from the Diaporthaceae and Botryosphaeriaceae families were isolated with a high incidence from rotten fruits. Here, we identify these pathogens from different plant parts (twigs, buds, and shoots) in orchards in the north-east of Hungary, and test their pathogenicity on immature nuts. Diaporthe eres Nitschke and Diplodia seriata De Notaris were identified in isolates from different symptomatic and asymptomatic plant parts based on their ITS (nuclear ribosomal internal transcribed spacer) and tef1 (translation elongation factor EF-1-alpha gene) DNA sequences. Purified monocultures caused rot of immature nuts following in vitro inoculation. Our results suggest that D. eres Nitschke and D. seriata De Notaris lingering on buds and overwintering woody parts may affect the seasonal nuts through wound infection. Infection by Diaporthe and Botryosphaeriaceae species present on woody plant parts, as well as on/in buds has been reported in Mediterranean countries. This is the first report of such stepwise aetiology from a region with continental weather. Climate change, associated weather patterns and the limitations of fungicide use in the European Union, among other factors, could be responsible for the increasing number of infections and economic damage caused by these pathogens.

Disparities in Agricultural Practices According to Cashew Nut Production Regions in Côte d’Ivoire and Probable Incidence on Nut Quality

Improving the quality of agricultural products depends largely on production process. In the absence of data on farmers’ practices and the average quality of cashew nuts in Cote d’Ivoire, the present study aimed to provide a detailed description of the cashew nut production process. Thus, a survey was carried out in the zones of Mankono, Dabakala and Bondoukou among 386 cashew producers selected at random and interviewed using the face-to-face technique. The results revealed that intercropping was practiced in cashew cultivation (42% - 62% of the producers), modern cultivation technique (72% - 98% of the producers) but with rare use of selected seeds (8% - 20% of the producers), labour/ha during nut harvesting (2.6 - 12 workers/ha). Concerning the harvesting process, the time taken to pick the nuts varies from 1 to 14 days; the use of pesticides during harvesting (14% to 97% of the producers) and the absence of sorting of the nuts in 42% of the Mankono producers justify the probable conservation of defective and immature nuts in their production. For drying, the main dryers were the slatted table, the cemented surface and the tarpaulin, but other dryers were found such as the mosquito net, the propylene rice bag, the fertiliser bag and the black bag. Generally, the drying time of cashew nuts was very short: 2 days (43% - 77% of the producers interviewed) but surprisingly 1 day (7% - 27% of the producers interviewed). For Mankono, the use of chemicals was permanent during all stages of the cashew production process. Overall, the results suggest the need to assess the real impact of farmers’ practices on the quality of cashew nuts from Cote d’Ivoire.

Mechanical Hedge Pruning Affects Nut Size, Nut Quality, Wind Damage, and Stem Water Potential of Pecan in Humid Conditions

Recent extensive pecan [Carya illinoinensis (Wangenh.) K. Koch] plantings coincided with a shift toward the planting of pecan trees at higher density by Georgia pecan producers in anticipation of maintaining these densities through hedge pruning. Initial studies of mechanical hedge pruning in the low-light environment of the southeastern United States have failed to show significant benefits to pecan production. The objectives of this study were to compare the effects of hedge pruning on pecan nut quality, yield, and midday stem water potential (ψ) of pecan trees in the temperate climate of the southeastern United States and to evaluate the effect of hedge pruning on windstorm damage to pecan trees. Treatments were arranged in a randomized complete block design with three blocks. Two treatments were evaluated; 1) Hedge-pruned; 2) Nonhedge-pruned (control). Midday stem ψ was 8.5%, 17.6%, and 16.6% higher (P ≤ 0.05), indicating less water stress, on hedged trees than on nonhedged trees during 2015, 2016, and 2017, respectively. Nut weight and percent kernel were increased (P ≤ 0.05) by hedge pruning 2 of 3 years of the study. Although no direct positive effect of hedge pruning on in-shell nut yield was observed, hedge pruning was not detrimental to pecan yield in the short term. Hurricane/Tropical Storm Irma brought damaging winds to the entire pecan-producing region of Georgia on 11 Sept. 2017, resulting in blown down trees, broken branches, and immature nuts blown from the trees. Hedged trees had 60% less wind damage in the form of major limb breakage and tree loss than did nonhedged trees.

Effects of early harvest times on nut quality and physiological characteristics of pistachio (Pistacia vera) trees

Introduction - Pistachio harvesting at the appropriate time is one of the key factors affecting the product quality. The effects of early harvest time on quantitative and qualitative properties of pistachio nuts were investigated. Materials and methods - The 'Ohadi' pistachio cultivar was used as the market reference in Iran. Five harvest times (July 27, August 6, August 16, August 27 and September 6) were studied over four consecutive years (2008-2011) as treatments in the field experiment. Nut weight parameters, hull discoloration, hulling, cracked nuts, early-split nuts, kernel protein, mineral and chlorophyll contents were evaluated at each harvest time. Results and discussion - The fresh and dry nut weights showed the maximum and the minimum nut production rates for the last (September 6) and the first (July 27) harvest times, respectively. Percentages of hull discoloration, cracked nuts and immature nuts were significantly influenced by harvest time. The early-split nut percentage was not significantly different at the various harvest times. The maximum potassium, calcium, magnesium and nitrogen, protein and chlorophyll contents were obtained at the first harvest time. The growth of current year shoots, leaf area, percentages of vegetative and reproductive buds were not influenced by the harvest time, whereas the abscission of reproductive buds was minimum at the first harvest time and significantly different from all other times. Conclusion - Early harvesting of pistachio is preferable in terms of crop health indicators, nutritional value and color of the kernels. However, it is not preferable in terms of yield (nut and kernel production per hectare) for the producers, although potentially more sustainable.

The infection process of chestnut rot, an important disease caused by Gnomoniopsis smithogilvyi (Gnomoniaceae, Diaporthales) in Oceania and Europe

Chestnut rot is an important disease of chestnut trees in Oceania (Australia, New Zealand), and Europe (Italy, France, Switzerland, United Kingdom). The causal agent has been identified as the fungus Gnomoniopsis smithogilvyi (Gnomoniaceae, Diaporthales). Koch’s Postulates was demonstrated on nuts from three Australian chestnut varieties with G. smithogilvyi from Australia, New Zealand and Italy. The Australian and New Zealand isolates were pathogenic on all three varieties, however the Italian isolate produced smaller lesions on all three, and was only mildly pathogenic on Decoppi Marone. Infection of chestnut floral and vegetative tissues was investigated during the chestnut phenological stages of flowering (sampled twice over two years), immature nuts and burrs, mature nuts and burrs, and tree dormancy (immature nuts and burrs, mature nuts and burrs, and tree dormancy were sampled once in one year). Gnomoniopsis smithogilvyi was present in all the sampled phenological stages, most frequently from female flowers during the flowering period. In the first year, the fungus infected 82% of female flowers, while in the second year only 10% were infected. Ascospore trapping in a laboratory chamber experiment confirmed ascopores are released in to the air from infected burrs. Ascospore trapping in an Australian chestnut orchard during the flowering period also showed ascospores are released in to the air, with peak trapping times at sunset and the hours following sunset (8-11 pm), and the hours following sunrise (7-9 am). These experiments support the hypothesis that ascospores of G. smithogilvyi infect chestnut trees, particularly the flowers. The fungus then exists as a latent pathogen in reproductive and vegetative tissues, leading to the development of the disease during nut maturity.

New era for the coconut sector. What prospects for research?

For years and years, the main output of the coconut sector on the international market was copra, crude coconut oil (CNO) and its derivatives. However, since approximately 10 years, we see new products so called “non-traditional” products entering global exchanges. The market growth of these products, mainly coconut water extracted from mature or immature nuts, virgin coconut oil (VCO) cold pressed from the fresh kernel, coconut sugar taken from the sap flowing out of the flower, is exponential. They benefit from the healthy, simple and natural image that is conveyed by the coconut tree in the subconscious minds of the consumers. The craze for this new products create also biggest expectative from the consumers towards the coconut stakeholders. This is why this article will also suggest some tracks of reflection for the research and expert’s communities, who would like to support this expansion, thus contributing to the future of the millions of small coconut farmers.

Biological Cycle of Bug <i>Pseudotheraptus devastans</i> Distant (Heteroptera: Coreidae), the Coconut Pest in Côte d’Ivoire

Pseudotheraptus devastans Distant (Heteroptera: Coreidae), is an important coconut pest in C?te d’Ivoire. The stings from Nymph and adult cause not only the falling of immature nuts, but also their deformation. This triggers losses of production in the order can reach 80%. Little information is available about this pest. Those existing are limited to its ecology and damages caused in host-plants. The present investigation is aimed to study the life cycle of this pest. The experiment was carried out in a coconut field of the Marc Delorme Coconut Research Station (MDCRS). On these coconut palms, bunches between 3 and 4 months of age, enclosed in cage were used. Development duration from an egg to adult emergence averaged 28.26 days. The average incubation period was on average 6.63 days and fertility rate of eggs was 98.01%. Nymphal development period was 21.63 days. The sex-ratio is in favour of females which live 112.6 ± 13.45 days. These females laid on average 198.85 ± 36.05 eggs. The males lived on average 131.3 ± 17.7 days. The knowledge of these different parameters could allow the development of a control method based on the breaking of life cycle of this pest.

Assessment of Bacterial Blight Tolerance of Persian Walnut Based on Immature Nut Test

Bacterial blight is one of the most serious diseases affecting Persian walnut (Juglans regia L.). Susceptibility to this disease was evaluated by artificial inoculation in an in vitro experiment for cultivars developed in Hungary and for selections from Transylvania. Thirty pieces of immature fruit of 11 walnut cultivars and 10 selections were inoculated by punction using a suspension containing a mixture of Xaj-isolates of controlled virulence. As control, a moderate resistant (mR) ‘Pedro’ and a highly susceptible (hS) ‘Milotai intenzív’ cultivars were used. After ten days the diameter of the necrotic area around the inoculation points was measured and the disease rate (DR) was noted. For the calculation of indexes it was taken the structure of the lesions (diffuse or defined margin) into consideration. None of the 21 cultivars/selections analysed were found to be hardly resistant, although all of them showed a higher degree of resistance than the susceptible control (‘Milotai intenzív’). The majority of the analysed cultivars fit into the moderate susceptible (mS) and moderate resistant (mR) group. ‘Milotai kései’ and SZEN-10, had a notable reaction as considered to be moderate resistant (mR), showed a similar degree of resistance compared to the control cultivar ‘Pedro’. It was concluded that these cultivars, based on their resistance to Xanthomonas arboricola pv. juglandis, could be proposed as resistance gene sources, as well as for production purposes in the environmental conditions of the Carpathian Basin.

Assessment of Bacterial Blight Tolerance of Persian Walnut Based on Immature Nut Test

Bacterial blight is one of the most serious diseases affecting Persian walnut (Juglans regia L.). Susceptibility to this disease was evaluated by artificial inoculation in an in vitro experiment for cultivars developed in Hungary and for selections from Transylvania. Thirty pieces of immature fruit of 11 walnut cultivars and 10 selections were inoculated by punction using a suspension containing a mixture of Xaj-isolates of controlled virulence. As control, a moderate resistant (mR) ‘Pedro’ and a highly susceptible (hS) ‘Milotai intenzív’ cultivars were used. After ten days the diameter of the necrotic area around the inoculation points was measured and the disease rate (DR) was noted. For the calculation of indexes it was taken the structure of the lesions (diffuse or defined margin) into consideration. None of the 21 cultivars/selections analysed were found to be hardly resistant, although all of them showed a higher degree of resistance than the susceptible control (‘Milotai intenzív’). The majority of the analysed cultivars fit into the moderate susceptible (mS) and moderate resistant (mR) group. ‘Milotai kései’ and SZEN-10, had a notable reaction as considered to be moderate resistant (mR), showed a similar degree of resistance compared to the control cultivar ‘Pedro’. It was concluded that these cultivars, based on their resistance to Xanthomonas arboricola pv. juglandis, could be proposed as resistance gene sources, as well as for production purposes in the environmental conditions of the Carpathian Basin.

REARING OF RED WEAVER ANT (OECOPHYLLA SMARAGDINA F.) FOR THE MANAGEMENT OF HELOPELTIS ANTONII SIGN. (HEMIPTERA: MIRIDAE) IN CASHEW (ANACARDIUM OCCIDENTALE L.)

Helopeltis antonii Sign. is the most serious pest of cashew in all cashew-growing areas of Sri Lanka. It feeds on the tender succulent shoots, inflorescences, immature nuts and apples resulting in drying of shoots, blighting of inflorescences and immature nut fall. In large scale cashew growing, insecticide spraying for the management of Helopeltis is the only effective method that has been practiced by many cashew growers. However, high cost of insecticides and insecticide application, chemical residues in cashew nut, reduction of beneficial organism like pollinators and other natural enemies of pests, development of pests’ resistance to pesticides and environmental pollution are major disadvantage of that method. On the contrary, biological control would be of high importance for the pest management in cashew as more sustainable and eco-friendly method. Several natural enemies of Helopeltis antonii were recorded in cashew plantations. Among them red weaver ant Oecophylla smaragdina F. (Hymenoptera: Formicidae) was observed with relatively higher population densities. Therefore, an experiment was conducted to ascertain the feasibility to use red weaver ant as effective biological control agent for the management of H. antonii in cashew lands. A red weaver ant (Oecophylla smaragdina F.) population was maintained during four consecutive years in an experimental site at Kamandoluwa cashew plantation. The experimental site was divided into two separate blocks. One block was introduced with red weaver ants and the other one was kept without ants. Ant nests were used for introduction of red weaver ants into the site for successful colonization. Data on yield, severity of the damage at different flushing stages of the trees were recorded during the experimental period (2005-2008). Yield data of the four years were analyzed by ‘Pool t’ test. A preliminary study was carried out to assess the predatory action of red weaver ant on Helopeltis under laboratory conditions and results were analyzed by Chi-Square test. Predatory action, nesting and foraging behaviour of ants were observed under field and laboratory conditions. A significant yield reduction was observed (P<0.05) in the block where red ants were not introduced compared to the block with red ants introduction. Chi-Square on predation were 72.78 (P<0.0001) and 97.63 (P<0.0001) for adult and nymphs of Helopeltis, respectively. Results revealed that the red weaver ants (Oecophylla smaragdina F.) are efficient predators on Helopeltis antonii Sign. having potential for the management of that pest in cashew plantations.

Screening Coconut Cultivars for Tolerance to Infestation by the Coconut Mite, Aceria guerreronis (Keifer) in Sri Lanka

The coconut mite (Aceria guerreronis Keifer) is a tiny pest which severely damages the nuts of the coconut palm (Cocos nucifera Linnaeus). At present there is no appropriate control method for this pest in Sri Lanka. Field observations have revealed difference in the severity of A. guerreronis mite infestation among selected and improved coconut cultivars in Sri Lanka. This difference has not been studied in depth and therefore the present study was conducted to investigate the levels of tolerance in selected and improved coconut cultivars and, if differences were demonstrated, to understand the mechanism behind the tolerance. A replicated trial in Thammenna Estate (TE) in Puttalam district in Sri Lanka, where the mite infestation was natural and severe, was selected for this study. The trial was planted in 1983 and consisted of two improved coconut cultivars; Sri Lanka Yellow Dwarf x Sri Lanka Tall (YDT) and Sri Lanka Green Dwarf x Sri Lanka Tall (GDT) and the selected Sri Lanka Tall cultivar (TT) which has, green (TTG) and russet coloured (TTR) forms. Population assessment of mites on immature nuts, damage initiation of the fourth bunch and harvest records were obtained. Further, characters that were thought to influence tolerance, such as nut shape as measured by ratio of length to breadth, the tightness of perianth to the nut surface and some changes in the affected tissues were also recorded. Yield data were collected for each cultivar to estimate the crop loss due to coconut mite damage. The results revealed that out of the cultivars tested in this trial, YDT had the lowest incidence of mite colonization and the smallest mite population size and symptom initiation compared to others. The distance between the perianth and nut surface, the least in YDT, is suggested as the most probable morphological feature that would impart tolerance to mite infestation.

English

&nbsp; Sensory characteristics of coconut water from four coconut cultivars (Cocos nucifera&nbsp;L.) were investigated during nuts ripening. The study was carried out on the West African Tall, the Malaysian Yellow Dwarf, the Equatorial Guinea Green Dwarf and the improved hybrid PB121. Tested parameters were tastes (sweet, salty and sour), gustatory preferences and sugars contents. Obtained results showed significant interactions between cultivars and maturity stages for analyzed parameters. So, during the ripening of nuts, the sweet taste of coconut water predominated according to the maturity stages. It was maximal at the rank 21 of dwarf cultivars with perception equivalent from 5.80 to 6.10% sugars contents. At full maturity, the coconut water sweet taste lowers because its sugars enhance the formation of the kernel. The results of hedonic tests led to the preference of the coconut water according to its sweet taste. So, the water of dwarf cultivars immature nuts, more sweetened, was the most appreciated. Sugars contents are specific for cultivars and maturity stages. Their values were maximal at ranks 19 and 21 of dwarf cultivars. Moreover, gustative data were closed to those of the sweet taste perception. This study allowed to determinate the sensory characteristics of the coconut water in order to give indicators for its efficient technological promotion. &nbsp; Key words:&nbsp;Coconut water, sensory tests, sugars contents, cultivars, ripening.

The decline of the Vulnerable yeheb Cordeauxia edulis, an economically important dryland shrub of Ethiopia

AbstractCordeauxia edulis (Leguminosae: Caesalpinioideae), commonly called yeheb, is a small tree/shrub species endemic to Ethiopia and Somalia. The tree produces nuts that are consumed as a staple food by pastoralists and are sold in local markets. Recent reports indicate that C. edulis has vanished from many locations where it was noted by earlier travellers and, as a result, it is currently categorized as Vulnerable on the IUCN Red List. To assess the current status of the species we studied it around 10 villages in Boh district in the Somali Regional State of Ethiopia, where the only known remnant stands of C. edulis in Ethiopia are found. The results show that these populations of C. edulis are declining and natural regeneration is negligible. We recommend that yeheb should be categorized as Endangered on the IUCN Red List, based on criteria A1d, because we estimate that there has been at least a 70% reduction in population size from overexploitation. The major constraints to natural regeneration and imbalance in the population structure are over-harvesting of immature nuts, excessive browsing of shoots and leaves by livestock and excessive cutting of wood for fuel and construction. We recommend that conservation measures for the species focus on sustainable harvesting of mature nuts, raising awareness among local people, preservation and monitoring of remnant populations and introduction of the species in ecologically suitable sites.

BIOLOGICAL CONTROL OF BACTERIAL BLIGHT OF WALNUT BY ANTAGONISTIC BACTERIA

The goal of this study was to determine whether bacterial antagonists could be used to control Xanthomonas arboricola pv. juglandis (Xaj), the causal agent of bacterial blight of walnut. A total of 35 potentially bacterial antagonists, 29 of which were isolated as epiphytes from the phylloplane of healthy walnut trees, were screened for their in vitro biological control activity against Xaj. Pantoea vegans strain C9/1 was also tested as reference biological control agent. Eighteen strains, that inhibited the growth of Xaj between 3.0 mm to 13.0 mm on TSA medium, were selected and further tested for their ability to control bacterial blight on immature nuts. Approximately 60% of the antagonistic strains, significantly reduced bacterial blight by 41% to 77% as compared to the positive control. Bacterial antagonistic strains, which effectively inhibited the development of Xaj on immature nuts were selected for further testing on walnut seedlings. Antagonistic strains were sprayed in a suspension of 109 CFU ml–1 on the leaves which were subsequently inoculated with suspension of Xaj strain W7/1 (108 CFU ml-1), 24 h after the antagonist treatments. According to the in vivo biocontrol tests on walnut seedlings (cv. Chandler), 4 putative antagonists significantly reduced the symptoms on walnut leaves (41% to 82%) compared with the positive conttol. Strains WH77/1, WH68 and WH48/1A were the most effective in the seedling test, yielding 55%, 42%, and 82% disease reduction, respectively, in two consecutive years. These strains were tentatively identified as Pseudomonas fluorescens on the basis of biochemical and physiological tests. P. vagans strain C9/1 agent, reduced the severity of bacterial blight on the leaves by 71%. The results obtained both nut and seedling tests agreed, except for P. fluorescens strain WH55/4 which was less effective in inhibiting symptom development in walnut leaves than in the fruits. Prohexadione-Ca (Pro- Ca) treatments of walnut leaves reduced by 66% blight symptoms.

Development of DNA Barcode and Species-Specific Markers forHelopeltis antoniiSignoret andPachypeltis maesarum(Kirkaldy) (Heteroptera: Miridae), Pests of Cashew in India

Some species of mirids are major pests of cashew damaging tender shoots, inflorescence, immature nuts, and apples at various stages of development. In India, crop loss is often more than 40% in cashew alone, and the genus Helopeltis closely resembles the genus Pachypeltis. Using molecular biology tools, morphological identification is further strengthened by DNA barcoding (using COX-1) and development of species-specific markers, which helps a non-specialist to identify a species. The molecular identification of Helopeltis and Pachypeltis spp. has been corroborated with morphological identification. The investigation results help in quick, accurate, and timely identification of Helopeltis antonii and Pachypeltis maesarum, a critical factor in understanding the epidemiology of the crop losses in cashew, their management and also in quarantine.

A PRELIMINARY STUDY ON IMMATURE NUTFALL OF COCONUT WITH REFERENCE TO PEST DAMAGE

A PRELIMINARY STUDY ON IMMATURE NUTFALL OF COCONUT WITH REFERENCE TO PEST DAMAGE

AN EPIDEMIC OF GNOMONIA PASCOE ON NUTS OF CASTANEA SATIVA IN THE CUNEO AREA

Since 2005, chestnut growers have observed increasing losses in yield in some sweet chestnut orchards lying to the South of Cuneo. In 2007-2008 a health survey was carried out on branches, flowers and developing nuts. A fungus was constantly isolated from the bark, but not from the xylem, of 1 to 3-year old branches, fruit stem, burrs, and with a variable frequency from the stigmas and styles. The fungus could not be isolated from the inner layer of the hylum. It was isolated sporadically from the nuts just after the fruit setting and with frequency increasing 25-80% in 2007 and 4-84% in 2008, in completely ripened nuts. In the diseased nuts, small chalky areas originate at the ripening time from the endosperm outer layers, and develop towards the centre of the kernel; progressively their color turns brown and the endosperm mummifies; the pathogen colonizes the pellicle and the shell on which it produces 122x85 - 251 x 171 μm, globose, black, pycnidium-like acervuli, that split open along the top and release a slimy, globular mass of conidia. Conidia are pale brown, one-celled, ovoid-oblong, biguttulate, 6.1-7.32 x 2.44-2.68 μm. This fungus, being able to colonize asymptomatically the branches and the immature nuts, has an endophytic life style with a true pathological behavior only on the ripened nuts. It is likely that it is unable to colonize the endosperm through the stem. It reproduced the disease in artificially inoculated healthy nuts, and endophytically colonized artificially inoculated chestnut branches. On the basis of such characteristics, the pathogen has been identified as Discula pascoe sp. nov., the anamorphic stage of Gnomonia pascoe sp. nov., a pathogen recently reported in the rainy areas of Australia and New Zealand. The territorial distribution, the epidemiology and the systematic characterization of the pathogen through phylogenetic analyses by unilocus and multilocus markers are under investigation.

Reaction of dwarf cashew clones to Colletotrichum gloeosporioides isolates in controlled environment

The cashew (Anacardium occidentale L.) crop is an important source of income for the population of the Brazilian Northeast, and anthracnose disease caused by Colletotrichum gloeosporioides leads to significant production loss. However, there is little information on either the host resistance or the variation in the aggressiveness of the pathogen under controlled environment. The reaction of commercial (CCP-06, CCP-09, CCP-76 and CCP-1001) and one non-commercial (CAP-14) dwarf cashew clones was assessed against 36 isolates of this fungus controlled environmental conditions. All the isolates, including those from hosts other than cashew, were able to cause lesions on leaves and stems of most clones, albeit to different degrees. Clone CCP-06 was the most susceptible, while clone CCP-1001 showed a level of resistance to a number of the isolates, including isolate 905, while isolates 910 and 912 were aggressive to all clones. Injury increased the susceptibility of the clones to all isolates, indicating that resistance also might be associated with structural barriers that hinder penetration. Ripened cashew apples (8-week-old), of commercial clones were susceptible to isolates 905 and 910. Immature pseudo-fruits (2-week-old), with exception of clone CCP-76 which was susceptible to both isolates showed resistance against these isolates, suggesting the presence of structural and chemical barriers. Developed nuts (8-week-old), however, were more resistant than immature nuts (2-week-old) to both isolates, probably due to their thicker exocarp cuticle and reduced number of stomatal pores.