Category Archives: Volume 6

Occurrence of a Chlorotic Spotting Disease on Some VISCA Sweet Potato Hybrids


Author(s): Ruben M. Gapasin and Ma. Leticia Suico

Abstract

A chlorotic spotting disease of sweet potato was observed during ions conducted in September 1984 on the sweet potato varieties and hybrids grown in the experimental field of the Visayas State College of Agriculture (ViSCA) Baybay, Leyte, Philippines. The disease believed to be caused by a virus. It was found to occur on variety VSP-2 and the hybrids V7 -27, V5-88. V3-44 and V3 -180.
Infected newly formed leaves of VSP-2 sweet potato variety showed systemic interveinal chlorotic spots while ring-spotting with indistinct borders appeared on older, fully expanded leaves (Fig. 1).
On the hybrids V7-27, V3-44 and V3-180, systemic interveinal chlorotic spots on the newly opened leaves were evident (Fig. 2) while ring spotting which later on coalesced, giving a mild mottled appearance was noted on fully expanded leaves. Formation of lateral buds was enhanced especially on V7-27 plants.
Interveinal chlorosis to mottling was observed in newly opened leaves of V5-88 sweet potato hybrid. Older leaves showed faint veinal chlorosis.
The ring spots usually faded 2-4 weeks after first appearance.
Preliminary transmission studies conducted by the authors revealed that the disease was transmitted mechanically and biologically by the cotton aphid (Aphis gossypii Glover) to healthy VSP-2 and V7 -27 plants.
This is the first time that the chlorotic spot disease of sweet potato was observed and reported to occur in ViSCA sweet potato hybrids in the Philippines. However, Benigno et al. reported a mosaic-type disease of sweet potato in 1974. It is necessary that studies on transmission, host range, physical properties, serology and electron microscopy be conducted to determine the identity of the virus.

:

Full PDF :
pdf

Crop Rotation of Sweet Potato, Cassava, and Gabi with Legumes as a Cultural Management System


Author(s): Alfredo B. Escasinas and Rodolfo G. Escalada

Abstract

Mungbean, bushbean, soybean and peanut planted in rotation with sweet potato did not significantly affect the vine length and fresh weight of the vegetative parts of the root crop but increased its marketable and total tuber yield. However, only the plants rotated with mungbean showed a significant increase in yield over the control. Rotation planting of cassava with leguminous crops did not affect its yield and yield components as well as the agronomic characters studied. Planting gabi in rotation with peanut significantly increased corm production compared with the mungbean and bushbean treatments. No pronounced effect of the other treatments on yield was noted. The weight of corms Per Plant and the corm yield per hectare of gabi showed similar response to the treatments while the number of runners per plant and plant height were not significantly affected by the treatments. Cost and return analysis showed that among the legumes used as rotation crops, peanut yielded the highest combined net return regardless of the root crop used. This manifests that peanut-root crop rotation is the most Profitable cropping pattern.

Keywords : Crop rotation. Root crops. Legumes. Cultural management. Cropping system.

Full PDF :
pdf

Economic Contributions of the Carabao to Farm Households and Resource Productivity Analyses


Author(s): Nerelito P. Pascual and Edgardo A. Panares

Abstract

Majority of the carabaos raised by farmers in Iloilo, Bohol and Leyte are intended primarily for draft purpose. Among the six types of farming systems, the carabao used for rice-based farming had the highest value of draft Power and the lowest was in sugarcane-based farming. The value of work done per year was highest in medium-sized farms, followed by those in large farms and small-sized farms based on both on-farm and off-farm operations in the three provinces. The animal work days per year rang. from an average of 23 days in small-sized farms to 37 days in medium-sized ones with an overall average of 30 days. Only three farmer respondents with one carabao each were milking their carabaos primarily for home use. Multiple regression analysis showed no significant relationship between number of work days and items of expenditure like depreciation, biologics and fees. Labor and cost of supplies and materials were found to be positively related to the number of work days. Total value of the economic contribution to the farm household showed no significant relationships with depreciation, supplies and materials, biologics and fees. Labor cost had a significant negative effect while farms size showed a positive effect on the total value of the economic contribution of the carabao to the farm household.

Keywords : Carabao. Farming system. Farm size. Economic contribution.

Full PDF :
pdf

Performance of Meat-type Ducklings on Different Levels of Feed Restriction


Author: Ebenezer T. Parrilla

Abstract

Body weights were reduced when ducklings were subjected to restricted feeding. However, no significant differences in body weights were obtained among treatments at 9 weeks old. The average fasted weights, uneviscerated weights, carcass weights (with and without giblets), and dressing percentages as well as the percentage of cut-up parts such as thighs, drumsticks, wings, neck, tail-back and rib-back were not significantly affected by feed restriction. However, the breasts of fully-fed ducklings were heavier and had higher percentage values than those of the restricted ducklings. Feed restriction also did not statistically influence the weights and percentage values of the giblets, head, blood, shanks and intestines. Highest returns-above-feed-and-duckling-costs can be derived when ducklings are marketed at 6 weeks of age. Ducklings whose feeds were restricted had higher returns-above-feed-and-duckling-costs than the fully-fed ducklings at later stages.

Keywords : White pekin duck (Anas platyrhynchos). Meat-type. Feed restrictions. Performance.

Full PDF :
pdf

Araceous and Nonaraceous Hosts of Taro Feathery Mosaic Disease


Author(s): Manuel K. Palomar, Joji Y. Duatin and Victoria G. Palermo

Abstract

Six plant species belonging to Araceae and one species of Solanaceae were infected with two taro feathery mosaic disease. Typhonium trilobalum (Linn.) Schott, Dieffenbachia maculata, Dieffenbachia sp.. and Datura metel Blanco were highly susceptible while Xanthosoma sp. w. moderately susceptible. Caladium bicolor (Avit.) Vent showed stunting and leaf distortion while Cyrtosperma merkussii (Linn.) Schott was the only species which showed latent infection. Dieffenbachia spp. had an average incubation period of 4.5 days followed by D. metel with 7.8 days; T. trilobatum, 13.5 days; Xanthosoma sp., 14.4 days; C. bicolor, 17.6 days and C. merkussii, 14 days. Back-inoculation to taro showed the positive presence of taro feathery mosaic in these plants.

Keywords : Taro feathery mosaic disease. Alternate hosts. Symptoms. Manual inoculation. Back-inoculation. Latent infection. Araceae. Colocasia esculenta.

Full PDF :
pdf

Intercropping Sweet Potato with Legumes as a Cultural Management System


Author(s): Bernadette F. Quirol, Rodolfo G. Escalada, Fe A. Manatad

Abstract

The use of legume intercrops deduced the overall growth of sweet potato. The yield of sweet potato declined by as much as 17.78% while that of the legumes by 14.94% due to competition for nutrients and light between the main crop and the intercrops. However, inoculation of the legume intercrops with Rhizobium minimized the competition for nitrogen and allowed the sweet potato to develop enough herbage. Sweet potato intercropped with inoculated legumes produced root yield which was 6.5% higher than the intercropped with uninoculated legumes.
Significant differences were observed on the effects of legume intercrops and their interaction with inoculation on sweet potato productivity. Bushbean was a better intercrop than either mungbean or soybean because this legume matures earlier than the other two. Bushbean and mungbean increased sweet potato yield upon inoculation but inoculated soybean seemed to depress the yield of the root crop.
In general, inoculation of the legume intercrops and intercropping were more beneficial and profitable. Intercropping was 4 and 3.5 times more profitable than monoculture when the legumes were inoculated and uninoculated, respectively.

Keywords : cropping system. Root crop-legume intercropping. Monoculture. In-oculation. N-fixation.

Full PDF :
pdf

Resistance of Fifty-two sweet Potato [Ipomoea batatas (L) Lam.] Cultivars to Meloidogyne incognita and M. javanica


Author: Ruben M. Gapasin

Abstract

Of the 52 sweet potato cultivars screened, 13, 4, 7 and 28 were susceptible, moderately susceptible, moderately resistant and resistant, respectively, to Meloidogyne incognita With M. javanica, only one cultivar was found susceptible, one was moderately susceptible, three were moderately resistant and 47 were resistant.
Based on egg mass rating index, the most resistant cultivar to M. incognita was W-86 followed by L4-89, BPA-4 and Sinibastian whereas Gold Rush, Binicol, C1596-9, Catanduanes and BNAS — 51 were most susceptible. UPR was the only cultivar found susceptible to M. javanica.
Highly significant positive linear correlation was observed between resistance rating and the parameters used. viz., number of egg masses and root galls, nematode population in roots, egg mass and gall indices. Egg mass index was the main criterion us. in assessing resistance since galling index was inadequate because galls produced in sweet potato were small and indistinct.

Keywords : Sweet potato (Ipomoea batatas). Meloidogyne incognita. M. javanica. Resistance rating. Egg mass index. Galling index.

Full PDF :
pdf