Enhancing capacity for nematode management in small-scale banana cropping systems [in Quezon, Davao, Quirino, Laguna, Oriental Mindoro, and Cebu, Philippines]

Comparative surveys were conducted in small-scale banana cropping systems in the three main islands of the Philippines; Luzon (Quezon, Oriental Mindoro and Quirino provinces), Visayas (Cebu) and in Mindanao (Davao del Norte and Davao del Sur). A total of 529 root samples involving 37 cultivars were collected. Total root samples collected revealed that cultivars Latundan, Saba and Lakatan were most commonly grown in 3 sites in Luzon, while Cardaba, Latundan and Sab-a frequently found in Cebu and Cardaba, Latundan and Lakatan were common in Davao. Cuarenta Dias, Morado and Tampuhin were also collected in Luzon but in lesser extent. In terms of diversity of cultivars, the survey in Cebu province encountered the most number of different cultivars (20) while the wild cultivars of Musa balbisiana were collected in Luzon. Root damage assessment based on percent necrosis and dead roots found the Sabang Puti in Cebu obtained the highest % root necrosis(RN) of 76.0 and with 62.0% dead roots (DR) while Dwarf Cavendish gave 50.0% DR but with lower % RN. This was followed by Inabaniko in Oriental Mindoro with 46.0% RN, Pulo in Davao (40.0% RN and 30.0% DR) and Saba in Quezon and Morado in Quirino province both with 30% RN. In Quirino province, highest percent dead roots were observed in cultivars Morado and Cuarenta dias with 65% and 50%, respectively. Root galling was observed in all surveyed areas but in trace to less than 25% galling incidence only (RGI: 1.0-2.0) in cultivars Morado, Bungulan, Saba, Lakatan, Latundan and Mundo. Highest nematode counts per 10 gram root samples was observes in Latundan (727 individuals) and the least in cultivar Pacol with only 24 individual nematodes. Parent occurrence in nematodes species different in all surveyed sites. Radopholus similis were found most abundant in Davao province with 95.1% followed by 91.3%, 85.3% and 65.0% in Cebu, Quirino and Quezon, respectively, while Helicotylenchus multicinctus (59.0%) and Pratylenchus (87.0%) occurred in highest percentage in Oriental Mindoro. Root-knot nematode, Meloidogyne sp. was also present in all areas but in lesser extent. Other nematode species identified includes Rotylenchulus renitormis which found in Luzon, Tylenchorhynchus in Davao, while Rotylenchulus was observed both in Davao and Cebu provinces but in fewer numbers. A total of 36 different Philippine banana cultivars (Musa spp.) of varying genotypes were evaluated for resistance to burrowing nematode, Radopholus similis and root-knot nematode, Meloidogyne incognita, under greenhouse conditions. Resistance was evaluated based on plant growth parameters such as plant height, pseudostem girth, shoot and root and root weight, root damage such as percentage root necrosis, percentage dead roots, root galling index, and nematode reproduction. Under greenhouse condition, cultivars Ambon, Cuarenta Dias, Cardaba, Katali, Kinamay Dalaga, Morong Princesa, Tanggung and Musa balbisiana Acc. 98-085 were identified to b resistant/tolerant to R.similis. On the other hand cultivars Ambon, Pandili and Sulay Baguio were found resistant to M.incognita, whereas Cardaba, Datu, Katali, Kinamay Dalaga, Laknau, Manang, and Matavia were found tolerant. Four(4) Meloidogyne populations collected from the provinces of Quirino, Laguna and Oriental Mindoro were identified and differentiated based in morphology and morphometrics. Variations in head cap, head region, stylet, tail structures and shapes of adults males of Meloidogyne populations were observed. Similarly, differences in the body length and width, head height and width and lengths of stylet, esophagus, testis, spicule and tail in males were noted in each population. Among populations, morphometrics of egg and juveniles showed slight differences in the length and width. Critical evaluation of the dorsal arch, lateral field, striae and tail terminus of perineal patterns in females warranted identification of all populations as Meloidogyne incognita. Ten local banana cultivars from AA, AAA, AAB and BBB genome groups were evaluated for resistance and/or tolerance to M.incognita populations under greenhouse conditions. Compared to uninoculated plants, significant percent difference in plant height, pseudostem girth, shoot weight and root weight in all cultivars evaluated were observed. No source of resistance to M.incognita was found. At least all the tested genotypes were as moderately susceptible to highly susceptible to M.incognita populations. Final nematode count was lower than initial inoculum due to scarcity of the root recovered during evaluation. Correlations between nematode morphology and morphometrics and nematode aggressiveness of virulence to banana genotypes were not clearly established. Further study must be conducted to determine these information gaps. Comparative studies were conducted on three Radopholus similis populations collected from banana farms in Quezon, UPLB and Davao provinces in the Philippines Morphological and morphometrical studies on fifteen (15) individual female and male similis from each population showed variations within and between the three populations in total body length, maximum body width, tail length, width at anus, anterior and posterior ovary lengths, and testis and spicule lengths. Tail shape and cuticular structures were found truncate with smooth terminus and pointed to tapering with smooth terminus and pointed to tapering with smooth terminus on females and males, respectively. Reproductive fitness of the three R.similis populations was also compared on single carrot-disk culture as a function of time at 28degC using 20 adult females. The Davao population showed high nematode density and reproduction ratio at 8 weeks after inoculation. Low nematode density and reproduction ratio were observed in the Quezon population, but with higher reproduction rate at 5 weeks after inoculation, several weeks earlier than Davao and UPLB isolates. The population with most reproduction had a greater percentage of reproductive females than a population with less reproduction. Reproductivity table also showed the same trend as the