(O.R. S. T. O.M.) Laboratoire de Nématologie IN IVORY COAST ' Paper presented by MAMADOU DIOMANDE

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1 I OFFICE DE LA RECHERCHE SCIENTIFIQUE ET TECHNIQUE OUTRE-MER (O.R. S. T. O.M.) CENTRE D 'ADIOPODOUME B.P. V51 ABIDJAN (Côte d'ivoire) Laboratoire de Nématologie I ROOT KNOT NEMATODES ON UPLAND RICE (URYZA SATIVA &., O. GLABERRIMA) AND CASSAVA (MANIHOT ESCULENTA) IN IVORY COAST ' Paper presented by MAMADOU DIOMANDE at the 3rd I.M.P. regional planning and research confer.ence held at I. I.T.A., Ibadan, Nigeria.'.- November 16 thru 20,

2 Root knot nematodes on upland rice (Oryza sativa i. O. glaberrima) and cassava (Manihot esculenta) in Ivory Coast M. DIOMANDE '. ORSTOM - Abidjan., After reading the reports of Merny (1976) and Foturner (198l-), one gets a good general idea of the MeZoidogyne problems in the Ivory Coast. Most crops extensively grown in the country (food, fruit, fiber, vegetable and commercial crops) havè their associated Me 1oidog.yne population, although the cor responding potential damage is certainly ver y variable. Fortuner (1 981 ) indicates that Meloidogyne is the second important genus after HeZicotyZenchus on upland rice in the country in terms of abundance and frequency whe'reas Merny (1976) states that this nematode is a rrninor parasite of cassava. Rice and cassava being two of our major food crops, we have conducted some research work on them with regari to their relationships to MeZoidogyne spp. I. MELOIDOGYNE ON UPLAND RICE Meloidogyne is associated with upland rice in most countries where tkis crop is grown (Fortuner 8 Merny, 1979). Upland rice cultivars have been recently screened for resistance to MeZoidogyne spp. by Babatola (1980) here in Nigeria and Sharma in Brazil (1 981). Results indicate that most cultivars are susceptible to this nematode although few cultivars show some interesting level: of resistance. In Ivory Coast, we have screened 41 upland rice cul- tivars or resistance to M. incognita. We have also performed some microplot inoculations with. and without fertilizers in order to roughly evaluate the damage'done by M,. incognita to a popular uplanc rice. cultivars, IRAT 13.

3 A - Screening upland rice cultivars. 41 upland rice cultivars including 21 cultivars of Oryza sativa and 20 of O.gZaber- rima.were screened for resistance to M. incognita. 20 replicates of each cultivar were transplanted in PVC tubes (3 cm diam. by 28 cm long) at the rate of one plantltube. Each tube was inoculated with 1050 larvae of a mixture of 3 M. incognita populations. The data obtained 2 xonths later included count of characteristic roots (roots with apical swellings) and final populations in roots. Pene- tration and devklopment were subsequently studied on 6 selected cultivars including 3 of each Oryza species using the technique described by Cadet & Merny (1977). The results indicated that : (i) M.. incognita reproduces generally better on O. sazisa roots than on O. gtaberrima roots. (ii) O. sativa cultivars have significantly mo re characteristic roots than O. gtaberrima cultivars (table 1). It is concluded that O. sativa cultivars are more susceptible to M. incognita than O. gzaberrima cultivars. It must cultivars (e. g.,is 335 and IS 358) show some interesting level of resistance. (iii) penetration into roots is not different between the two rice species whereas development into adult females is better on O. sativa-cultivars (table 2). It seems that the more sus ce^ tible in the terms defined here, the more adult females are obtaine Resistance is therefore related to the development rather than to the penetration. be noticed however that few sativ The rice breeding team at IRAT in Bouakg has successfull-, made several interspecific crosses between O. sa-tiva and O. gtaber- rima but the progeny is always sterile. Breeding efforts are being pursued along this line. B - Microplot inoculations. M. incognita eggs were inoculated tc IRAT 13 growing in microplot with or without fertilizer at the rate of 100 O00 eggs/microplot (= 300 eggs/dm3 of soil). The following treatmentswere used in a factorial set up with 6 repetitions : O0 : No nematode no fertilizer ON : Nematode alone EO : Fertilizer alone. EN : Fertilizer and nematode

4 Resultscan be found in table 3 and figure 1. M. incognita does significantly decrease the number of tillers, the number of panicles, the plant height and the yield of IRAT 13. All these cha- racteristics can be improved by fertilization. These improvements, although at their best in the absence -of M. 5ncognita, are significani in the presence of the nematode. It is concluded that under certain circumstances, fertilization can largely compensate the effects of M. incognita on upland rice. In the light of new findings, we have observed that this nematode may prevent rice cultivars from respon- ding to fertklization. One can cbnclude that resistance germplasm to M. incognit exists in upland rice cultivars and that fertilization may help aleviate Meloidogyne problems under certain circumstances. II. MELOIDOGYNE ON CASSAVA. 3 The role played by cassava (Manihot e.scuzenta) in solving the food problem-in the Ivory Coast has always been significant and is actually increasing with large scale projects such as that of SODEPALM in Toumodi. More scientific attention is needed for this crop. From the paper of Dickson (1977), it is apparent that nematodes have not been adequately studied on cassava on a world- wide scale. The work of Caveness (1979) appears to be one of the major contributions in this area. We undertook this study in order to get an idea of the population dynamics of MeZoidogyne spp on two cassava cultivars. For this purpose, a test was setup on M. javanict infested plots on the ORSTOM farm and an inoculation test was conducted in the greenhouse. In the inoculation test, 7060 juvenile. of M. incognita and 7000 Praty Zenchus brachyurus were simultaneousl: inoculated to cutting-seedlings of the two most commonly used cassava clones (CB and Bonoua) in buckets. Non inoculated controls were included in the test. Every 15 days, 2 buckets of each treat- ment were emptied and the roots of the plants put in the mist chamber. The fiad test involved a DBCP treatment of a plot with a non treated control. Cuttings of CB and Bonoua were planted on both and every 15 days, 5 plants were uprocted in each treatment (removing as much of the róot system as possible) and the roots put in the mist chamber.

5 Results can be seen in table 4 and figure 2. These 2 cassava cultivars are not good hosts for MeZoidogyne incognita and M. javanieu since these nematodes do not reproduce well on them. No difference was found in the tuber yield between DBCP-treated and non treated plots. Plant. hights seemed better in treated than non treatec plots however. In the inoculation test, only the root weight of Bonoua decreased significantly, pr'sbably due to Pratylenchus rather than bleloidogyne. Since cassava is commonly associated with many other crops in traditionnal farming, the 2 cultivars tested here couldibe.usefu1 in Keeping.Meloidogyne populations down. Since Saka ìl Makina (1981) have shown that bitter cassava extract has some nematicidal property in Malawi, we' are looking.into such possibilities with these two cassava cultivars

6 . d. Table 1 - Final populations of MeZoidogyne incognita and number of characteristic roots on gzaberly.ima and sativa cultivars of upland rice in 2 months. GZaberrima. Nematode C haract eri s t i c vari e ties population roots IJ2/g1. (per plant1 CA V6 CG {lx. CG 13 CG 18 * - CG 24 CG 45 - CG 67 CG 74 CG 84" DG 15 LG-009 LG 052 LG 061 MG 007 MG 021 MG 029,. : OG 1 OG 008% OG 15 '' TO _ ,p ' l,o O, O,? * ,s , O Sativa Nematode Characteristic verieties population roots 152 /g1 (per plant " ACC x IGU-APE CATETO IRAT 13., MOR OB ER EK AN IS IS 168, IS 173x IS IS 251 IS c IS 276 IS 283 IS 289 IS 300 IS 302 IS IS Is 337 I 053 IS IO2 IS IS 350". 703 ' LSD 0,05 - Means 441,45 0,s '.' ' ,8 x Varieties selected for penetration and development studies. _.

7 . I Table 2 - Penetration and development of MeZoidogyne incognita juveniles in the roots of few upland rice varieties. S Ri ce % (11. % (21..% I21 penetration. males females varieties. OG l O a l d.. 2;1 O i. - n CG 11 16,3 c 3aO. 4,3 h -CG 84 ' 20,3 b. l a 9 7 a 9 g.. ACC ,4 c 25 f \.. - IS s2 b * IS ,3 a 6s 9 3aO -. 3,4 h.-. -.?Oa4 e II I average percentage of the 50 juveniles initially inoculated I21 average percentage of the penetrated juveniles. numbers followed by different letters are significantly different at 5%. \

8 -. Table 3 - * Effects of MeZoidogyne incognita on some characteristics of IRAT 13 with and/or without fertilization ~ Mean panicle Panicle fresh EfTective. * Mean plant Percentages (2) height length. weight, yield(1l. (cml [ cml. Ig/microplat 1 [g/microplptl ON (3 1 94B9 a 22B2 d 124 f 84,7 j. I00.. O0 107, 6 b d 22.0 g 160,2 k. 189 EN. 115,l. bc. * 26,2 e 300,7 hi 194,8 kl 229,9., 4 EO 124,9. c y [Il (23 (31 grain yield obtained after gravity separation of floating grains. The epfective yield of treatment ON i6 taken as 100..\ O0 = NO nematode no fertilizer - ON = nematode alone - EO = fertilizer alone - EN = fertilizer and nematode. Numbers followed by different letters are significantly different at the 5% level.

9 1 root1 Table 4 - Populations of Mekoidogyne javanica and PratyZenehus brachyurus on CB and Bonoua roots 3 months after inocula tion. Cassava cultivars final populations M. javanieu P. brachyurus * [J2/g of. Inemas/g of. root I roots dry weight [gl CB NON INOC ULATED O O 7.25 a i n o c u-1 a t e d a BONOUA non inoculated inoculated o 357 O a 3.-2 b I- -.

10 .:- Days after transplanting Fig. 3 (A - B) - Effects of MeZo{dogyne incogn{tq and/or fertilization on tillering CA) and panicle <setting CB) of JRAT 13. OQ = NO nematode no fertilizer - ON = Nematode alone EO = Fertilizer alone EN = Fkrtil4,zer and nematode... -.

11 O I ' \ o Big. 2 (A-B) - 'Populations of MeloidoKyne Javanica in the roots of CB and Ronoua (A) and in the soil (B) in 4 months.

12 I. REFERENCE S BABATOLA, (J.D.), Reactions of some rice cultivars to the root knot nematode, MeZdidogyne incognita. Nematropica 10 (1) : L s et CADET,(P.) i MERNY, (G.), Méthode d'étude de la pénétration du développement des 2 sexes chez les Heterodera. Cah. QRSTOM, sér..bioi.,. I1 : CAVENESS, (F.E.), Cowpea, linea bean, cassava, yams and MeZoidogyne sp-. in Nigeria. in root-knot nematodes (MeZoidogyne species) ; systematics, biology and control. LAMBERTI, (F.) & TAYLOR, (C.E.), Ed. Academic press... London, New York, San Francisco. pp DICRSON, (D.W.), Nematode problems on cassava, Proc. prot. workshop on cassava. C.I.A.T., Calï. Colombia; 7-12 Nov., pp DIOMANDE, (M.), Effets direct et combiné des engrais et.de MeZoidogyne incognita sur le riz de plateau. Rev. Nématol., 4 : J FORTUNER, (R.), 1977,- Fertilisation du riz et dégâts causés par le nematode HCrschmannieZZa oryzae (van Breda de Haan) Luc 8' Goodey, C.R. Hebd. Séanc. Acad. Agric. Fr. 58 : FORTUNER, (R.), Les -nématodes associés au riz pluvial en Côte d'ivoire. Agron.. Trop. 36 (1) : FORTUNER, (R.) 81 MERNY, (G.), Les nématodes parasites des racines du riz. Mise au point bibliographique. Rev. Nematol,. 2 (1) :

13 L a 4. e1 i i MERNY,.(G.), Root knot problems in Ivory Coast. Proc. IMP, Conf. June IITA, Abadan, Nigeria. SAKA,' (V.W.) 8 MAKINA, (D.W.), I981.- Nematicidal activities of.. acqueous extracts of "bitter" cassava peels and tung cake against MeZoidogyne javaniea.!ith Sympos. Nemat. Soc. South Africa : 7 (abstr.). SHAM, (R.D.), 1981.: Reactions of upland rice to root-knot nematode MeZoidogyne javaniea. Int. Conf. Trop. Crop prot., Lyon, France, 8-10 July (abstr.) -. I'