Coconut Research Institute Research Articles

MODELS OF TRAPS FOR THE COCONUT PESTS RHYNCOPHORUS BILINEATUS AND SCAPANES AUSTRALIS AND THEIR TRAPPING EFFICIENCY IN PAPUA NEW GUINEA

The beetle pests Scapanes australis, Oryctes rhinocerous and Rhyncophorus bilineatus have been major constraints to coconut production in the Islands region of Papua New Guinea for the last 30 years. Efficient synthetic attractants able to lure and trap all three beetles have been developed. This paper describes several trap designs developed at the Cocoa and Coconut Research Institute and the results obtained for their trapping efficiency in the laboratory and the field. A modification of the “Titus Bucket” trap increased the number of R. bilineatus caught threefold and of female Scapanes twofold. PVC pipe traps caught more Scapanes than the modified “Titus Bucket” trap.

Durability of Field Resistance to Black Pod Disease of Cacao in Papua New Guinea.

Black pod disease of cacao, caused by various species of Phytophthora, is one of the most serious causes of cacao yield losses worldwide. In Papua New Guinea, such losses on local smallholdings are estimated at more than 40% of annual production. Genetic improvement of cacao resistance is the most promising way of reducing the impact of these pathogens. Field infection of 25 selected Trinitario × Upper Amazonian hybrid progenies in a factorial design (5 by 5) was monitored for five consecutive years at the Cocoa and Coconut Research Institute in Papua New Guinea. The resistance durability of the various hybrids was analyzed using a factorial split-plot model with years as the main factor. The reaction of the hybrid progenies remained stable and similar throughout the 5 years. Similarly, the general combining ability ranking of the parents was also the same for each year. Moreover, data accumulated over several years provided a clearer distinction between the parents. The analyses clearly showed female inheritance under field conditions, and the progenies from what are believed to be resistant females showed good resistance.

FACTORS INFLUENCING THE PRODUCTIVITY OF COCONUT ESTATES

The yield gap between the potential and actual productivity has been widening in coconut estates (>9 ha) over the years. Among many reasons, the non-adoption and incorrect adoption of recommended agronomic and crop management practices on coconut cultivation have largely contributed to this yield gap. A survey carried out by the Coconut Research Institute (CRI) indicated that the lack of competent caretakers to correctly implement the crop management practices is a major reason to the yield gap and that there is an urgent demand for trained Farm Managers. Eight percent of the estates was identified as ‘poor’ with respect to the nut yield and the standard of the management practice adopted. Majority of both proprietors and caretakers (75%) was not satisfied with the productivity of their estates. The performance of the estates was significantly associated with the land suitability class of coconut and the uses of recommend practices. About 75% of the caretakers had not received any training on coconut cultivation. According to the perception of the proprietors, males between 25-30 years of age are the best group to be trained as Farm Managers. The training course should include theory and practice on all aspects of coconut cultivation, intercropping, animal production, labour management, accounting procedures in estates, and the use of agricultural machinery.

COCONUT NUTRITION IN PAPUA NEW GUINEA

Copra yield in Papua New Guinea is estimated at 0.6 tonnes per hectare per year. Several factors may be responsible for this low productivity compared to other Asia Pacific countries. Amongst these, nutrient deficiency is an important limiting factor. In order to evaluate coconut nutrition status in PNG, leaf sample collection was undertaken by examining 23 sites around the country and from a nutrition trial carried out at the Stewart Research Station of the PNG Cocoa & Coconut Research Institute (PNG-CCRI) in the Madang Province. Results of leaf analysis revealed significant widespread nitrogen deficiencies at most of the sampled sites and geographic variations in potash deficiency. Chlorine deficiency varied with geographic sites and was closely related to the prevailing wind pattern. Preliminary results on nut-set and flowering in the trial at Stewart Research Station revealed a positive response to nitrogen and chlorine-based fertilizer applications. This suggests that appropriate fertilizer applications would be benefit future coconut production on this particular site.

Biological nitrogen fixation in four Gliricidia sepium genotypes

A field experiment was conducted at the Coconut Research Institute in Sri Lanka to examine the biological nitrogen fixation potential of three Gliricidia sepium provenances (OFI 14/84, 17/84, 12/86) and a local landrace (designated LL), using the 15N isotope dilution method. There was marked variation in dry matter, total N, nodulation and 15N enrichment among the Gliricidia genotypes (=0.001), and the dry matter yield of Cassia siamea (syn. Senna siamea), the non-N2 fixing reference plant was higher than for G. sepium. In all cases, highest biomass and total N were aboveground, with roots on average accounting for < 20 % of total dry matter or the total N in plants. Atom % 15N excess was highest in C. siamea, and lowest in OFI 14/84. Although atom % 15N excess was lower in Gliricidia leaves than in the other organs (all of which had similar 15N enrichments), values of % N derived from atmospheric N2 fixation (% Ndfa) calculated for any individual organ or for the whole plant were similar. This was because the relative distribution of 15N in the different parts of the fixing plant followed the same trend as in the reference plant. There were significant differences (p=0.01) in N2 fixation between the Gliricidia genotypes. The values ranged from 17.8 g N tree-1 (equivalent to 86 kg N ha-1 at 5000 trees ha-1) in OFI 12/86 to 61.7g N tree-1 (equivalent to 309 kg N ha-1) in OFI 14/84. Although most of this variability was due to differences in both % Ndfa and total N in plant, amount of N fixed was more correlated with total N in plant (r=0.935) than with % Ndfa (r=0.707). On average, % Ndfa in all three G. sepium provenances and LL was about 55 % or 34.6 g N tree-1 (equivalent to some 166 kg N ha-1) in the 9 months within which N2 fixation was measured. This represents a substantial contribution of N into the soil-plant system.

Statistical Analysis of Field Experiments in Coconut Using Fewer Recordings

SummaryCoconut is harvested at bimonthly intervals (six picks per year) in all field experiments carried out by the Coconut Research Institute in Sri Lanka. Because recording of individual picks is costly and time consuming, it is of interest to know whether or not recording can be restricted to fewer picks without prejudicing the results of experiments. Yield data from five long-term field experiments conducted at five different locations showed that the sum of the first, third and fifth picks could provide a good estimate of the sum of six picks. Yield recording can therefore be confined to these three picks and the cost and time of recording in an experiment reduced by 50%. These three picks can conveniently be used to assess treatment effects on total annual yield.Análisis estadístico del rendimiento de coco

Comparison of metalaxyl/cuprous oxide sprays and potassium phosphonate as sprays and trunk injections for control of Phytophthora palmivora pod rot and canker of cocoa

Field trials evaluating potassium phosphonate foliar sprays and trunk injection for control of Phytophthora palmivora pod rot and canker of cocoa ( Theobroma cacao L.), were conducted over two years at six commercial plantations and at the Papua New Guinea Cocoa and Coconut Research Institute, Keravat. Over a wide range of management inputs and environmental conditions, trunk injection of potassium phosphonate gave control of Phytophthora palmivora pod rot comparable to that obtained with conventional metalaxyl/cuprous oxide pod sprays. Significant reductions in pod rot incidence were obtained at five of the six plantations. Injection gave improved control of stem and branch cankers, resulting in negligible incidence at some sites. Potassium phosphonate foliar sprays gave poor control of both canker and pod rot and were less effective than either trunk injection or metalaxyl/cuprous oxide sprays.