Incidence of Phytophthora Fruit Rot on Four Durian Cultivars in Davao City, Philippines

A two-year study was conducted in a farm in Davao City, Philippines, to investigate the incidence of Phytophthora fruit rot on four commercial durian (Durio zibethinus Murr.) cultivars previously laboratory-tested for their reaction to the disease using isolates of the pathogen, Phytophthora palmivora Butler. In year 1, disease incidence was highest on cultivars Alcon Fancy and Arancillo at 10.7% and 9.9%, respectively. Lesser infection was observed on cultivar Puyat (0.5%) and no infection was recorded for cultivar Seri Kembangan. The same trend was obtained in year 2, further confirming previous laboratory infection test results. Incidence on Alcon Fancy was 47.3%, followed by Arancillo (25.92%), Puyat (12.6%), and Seri Kembangan (2.1%). In monetary terms, the year 1 total of 545 infected fruits is equivalent to a potential income loss of PhP27,250.00, with PhP2900.00, PhP2697.00 and PhP204.38, respectively, coming from the three cultivars. In year 2, the total of 1233 total infected fruits translates to a potential income loss of PhP49,320.00. To this figure, Alcon Fancy cultivar with the highest infection (47.3%) contributed PhP21,873.34, followed by Arancillo (25.9%) with PhP15,967.35. Puyat at 12.9% infection shared about PhP11,925.00 and Seri Kembangan at 2.1% added an equivalent of PhP1294.65. Result of the study indicate that more disease management interventions will have to be exerted for the more susceptible but more commercially preferred cultivars. Several fruit nursery operators in Davao City expressed that propagating Alcon Fancy and Arancillo seedlings is no longer profitable since knowlegeable farmers do not patronize them anymore, citing high susceptibility to Phytophthora diseases as the primary reason

Notes on Two Herbivorous Palm Weevil Species Associated with Sago Palms (Metroxylon sagu Rottb.) in the Philippines

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Nutrient Status of Nipa from Semi-Wild Stands in Selected Areas of Mindanao, Philippines

Nipa (Nypa fruticans Wurmb.) is a potential source of biofuel from its sap. Increasing sap yield requires understanding nutrient requirements of this palm necessary for cultural management practices. Hence, the nutrient status of nipa in its natural habitats (Western, Northern, Eastern, and Southern Mindanao) were determined to establish critical levels of essential elements using soil and leaf analyses. Results revealed that nipa palms thrived in a wide variety of soils from clayey, loamy to sandy clay loam types. Elemental variations were observed across sampling sites owing to their locations in the estuaries, human activities, and soil pH. Exchangeable bases Na, Ca, Mg, and K varied considerably across areas affecting leaf levels of nipa. However, leaf B levels were shown to be regulated even at toxicity levels of B in the soil. These growing conditions indicate that nipa palm can tolerate highly variable physico-chemical factors that exist in the estuaries. The critical levels of the essential elements in the leaf tissue are estimated as follows: 1.30±0.30% N, 0.13±0.03% P, 0.82±0.14% K, 0.12±0.29% Ca, 0.03±0.03% Mg, 0.16±0.13% Na, 0.53±0.10% S, 0.70±0.10 mg/ kg Cu, 4.30±0.90 mg/kg Zn, 20.00±2.30 mg/kg Fe, 64.20±31.70 mg/kg Mn, and 4.40±1.70% B. These leaf nutrient levels will serve as a basis for fertilizer formulation in nutrient management in the future

Nutrient Status of Nipa (Nypa fruticans Wurmb.) in Selected Areas of Mindanao, the Philippines

Nipa (Nypa fruticans Wurmb.) is a potential source of biofuel which requires the understanding the palm’s nutrition in order to increase sap yield. Initial baseline data on the nutrient levels of nipa were determined from its natural habitats in Mindanao using foliar analysis. Results revealed that nipa palms thrived in a wide variety of soils from clayey, loamy to sandy clay loam types. Elemental variations were observed across sampling sites owing to their locations in the estuaries, human activities, and soil pH. Leaf B levels were shown to be regulated even at extremely high levels in the soil. The nutrient levels in the leaf tissue using leaf rank 2 are as follows: 1.34±0.30% N, 0.13±0.03% P, 0.82±0.14% K, 0.03±0.02% Ca, 0.03±0.03% Mg, 0.16±0.13% Na, 0.53±0.12% S, 0.70±0.11 mg/kg Cu, 4.33±0.94 mg/kg Zn, 20.00±2.35 mg/kg Fe, 64.22±31.74 mg/kg Mn, and 4.45±1.67 mg/kg B. When compared across leaf ranks, mobile elements K and Mg were significantly higher in the youngest fully opened leaf rank 1. For Mn, leaf rank 3 was significantly higher than leaf rank 1, but leaf rank 2 did not vary with either leaf ranks. It is recommended to use leaf rank 2 for foliar analysis on the basis of its intermediate physiological age. Also, Cl level was higher compared to other elements indicating tolerance to saline conditions. Keywords: foliar analyses · leaf ranks · Nypa fruticans · nutrient

Infructescence Development and Seed Characterization of Nipa Palm from Different Semi-Wild Stands of Davao Region, Southern Philippines

The versatility of nipa even under unstable environmental conditions and its potential use as source of bioethanol underscore the importance of understanding the fruit development of the palm. Female anthesis served as the reference point for determining the age of infructescence (fruit head). Weekly observations categorized according to morphological changes showed that Stage 1 is distinguished by a hard brown seed with dark brown tips. Stage 2 is characterized by seeds of even brown hue with some carpels fused forming bigger seed. At Stage 3, the infructescence began to bend owing to its weight with seeds having brown color with darker hue. At 21 weeks from female anthesis, the fruit head reaches its peak of rapid growth, which may also level off photosynthate demand. This suggests a halt to being a ‘sink’ in the succeeding stages. At Stage 4, the infructescence was already bending halfway the ground level. At Stage 5, the fruit head finally touched the ground. This indicates full maturity at 25 weeks from onset of female anthesis. In a separate study, environmental variability did not show statistical differences on seed morphometrics. However, position of seeds in the infructescence significantly affected viability. Seeds, if spherical, are considered viable and were located in the polar end opposite the peduncle and in the equatorial region. Dark brown seeds indicate full maturity. This study would be of value in the future as reference for seed maturity index, variability tests, and description of different stages for timing sap collection during tapping

Infructescence Development and Fruit Characterization of Nipa (Nypa fruticans Wurmb.) from the Semi-Wild Stands of Davao Region, Philippines

The potential use of nipa (Nypa fruticans Wurmb.) as a source of bioethanol underscores the importance of understanding its infructescence (fruiting head) development beginning at female anthesis. Manual pollinationset-ups showed that stigmatic receptivity spanned 48 h with a peak at 36 h after onset of female anthesis. Weekly observations according to morphological changes at fruit set are categorized as follows: stage 1 is distinguished by the gradual hardening of exocarp and browning of fruits in the infructescence. The fruit color turned dark brown as development proceeded to stage 2 wherein some carpels fused forming bigger fruit. At stage 3, the infructescence began to bend owing to its weight with fruit color intensified to darker brown. At 21 weeks from female anthesis, the fruit head reaches its peak of rapid growth. The hanging of infructescence ensued at stage 4 that ultimately touched the ground at stage 5. This indicates full maturity at 25 weeks from the onset of female anthesis. In a separate study to characterize fruit development, fruit shape appears to be influenced by position in the infructescence rather than environmental conditions. Fruit samples categorized as developed had mostly spherical shape. They were likely located in strategic positions (polar end and equatorial region) of the infructescence which emerged first during female anthesis. A very dark brown hue indicated full fruit maturity

Yield and Response of First and Ratoon Crops of Eggplant (Solanum melongena) to the Eggplant Fruit and Shoot Borer (Leucinodes orbonalis) under an Integrated Pest Management System

Eggplant (Solanum melongena) is a highly valued crop with an average production of 10 t·ha–1 and contributes to nearly PhP2 billion in the Philippine economy using conventional farming methods. An integrated pest management system was designed to control the eggplant fruit and shoot borer (EFSB) for increased productivity with reduction on harmful pesticide inputs. Under a split plot in randomized complete block design, two eggplant varieties, i.e., hybrid Banate King F1 (BK) and open-pollinated Dumaguete Long Purple (DLP), were tested under four different pesticide treatments, namely, (1) control–no pesticide, (2) organic–Bird’s chilli extract, (3) synthetic–spinosad + flubendiamide, and (4) combination–Bird’s chilli extract + spinosad + flubendiamide. After data was obtained, the first crops were ratooned and tested under the same IPM system. Data on yield and EFSB damage of the ratoon crops were compared with the first crop as influenced by eggplant variety and pesticide treatment. All plants were grown on plots covered with polyethylene mulch sheets under a uniform fertilization and fungicide regimen. Multiple cropping with regular field sanitation and inspection were also incorporated in the IPM system. Results indicate that BK is a superior variety over DLP with a gross yield of about 40 t·ha–1 and a marketable yield of about 20 t·ha–1 in 22 harvests. Ratoon crops produced lower yield than first crops with only 2 t·ha–1 in 12 harvests. Among the pesticide treatments, synthetic or combination treatments are superior over the control (no pesticide) or organic treatments. Use of open-pollinated DLP and chilli spray is inferior to hybrid and synthetic or combination sprays. Chilli spray also tends to nullify the effectiveness of synthetic pesticides when used in combination. The designed IPM system produced higher yield than conventional methods, but all treatments only provided moderate control over EFSB damage with average yield losses of about 50% in first crops and about 60% in ratoon crops

Reactions of Six Durian Cultivars to Phytophthora Fruit Rot by Artificial Inoculation Under Controlled Conditions

Isolates of Phytophthora palmivora Butler obtained from rot-infected durian (Durio zibenthius Murr.) fruits were inoculated on healthy fruits of six durian cultivars (Alcon Fancy, Arancillo, Native, Puyat, Seri Kembangan F2 and Seri Kembangan Original). One mL of isolate suspensions (2.6 x 105 spores•mL) was applied on the midsection rind of each fruit (10 fruits per cultivar). Seri Kembangan F2, Alcon Fancy and Arancillo were the most susceptible to fruit rot in terms of rate of infection and lesion development. Puyat and Seri Kembangan Original had the least infection

Pestalotiopsis palmarum (Cooke) Steyaert: A Leaf-Pathogenic Fungus Associated with Sago Palm (Metroxylon sagu Rottb.) in the Philippines

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