Positive products for control of rice blast disease Mwangi J.K, - UOK Wanjogu R.K,Owilla B.P.O, -MIAD

Introduction Rice is one of the world’s most important cereal crop and its protection from disease is vital to the many million dependants on it as their staple food. Rice: 3rd most important cereal crop in Kenya ; Consumption: 400,000MT p.a Production constraints; Abiotic : drought and floods, temparature, soil fertility Biotic: insect pests, and diseases (Fungal and bacterial) Primary constraint;- Rice blast. Rice Blast Causal organism  Perfect stage: Magnaporthe grisea  Imperfect stage(anamorph): Pyricularia oryzae The fungus infects plant by the spore germinating and forming an appresorium (a thick fungal cell) on the plant surface and then exerting a haustoria (feeding structure) into the plant cells. A minimum of 8 hrs moisture is needed for infection to occur. Most plant parts are susceptible to infection except the roots..

Symptoms caused by Magnaporthe grisea on rice plants Collar blast Neck rot Panicle blast Leaf blast

Node symptom White heads' caused by neck rot Node blast Panicle blast

Introduction cont. Yield losses due to blast;- Approximately 60% - 100% Rice blast was first reported in Kenya in the 60’s mainly in the Western regions. It has also been reported since 2008 in Mwea the main rice growing area in the country where it caused % yield loss. The blast problem has threatened rice production and also the national food security. Use of resistance varieties against rice blast pathogen alone has been found to be unreliable and sometimes disappointing. Breeding for these resistant lines takes time before they reach the farmers. It thus seems that chemical control can offer greater promise and will constitute an important weapon in reducing crop losses. The objective of the trials is to evaluate the efficacy of different fungicides from different companies in the control of rice blast.

Fungicides presented thro PCPB for trials COMPANYPRODUCTCATEGORYNO. OF SEASONS COMPLETED CURRENT STATUS Green lifeJupiterFungicide2Report submitted to PCPB Green lifeWitnessFungicide2Report submitted to PCPB Green lifeChariotFungicide2Report submitted to PCPB Green lifeGoddardFungicide2Report submitted to PCPB Green lifeSacrifidoFungicide2Report submitted to PCPB Green lifeDefactoFungicide1First season data entry is ongoing Green lifeExempo curveFungicide1First season data entry is ongoing Green lifeAbsoluteFungicide1First season data entry is ongoing Green lifeRansomFungicide1First season data analysis ongoing, second season trial ongoing in the field SygentaScoreFungicide2Report submitted to PCPB SygentaAmistarFungicide2Report submitted to PCPB SygentaArmureFungicide0First season trial ongoing in the field Top serveStallionFungicide2Data analysis and report preparation ongoing Green lifeDiscoveryFungicide (Sheath Blight) 0Field preparations in progress East Africa B. Company BlastinFungicide0Field preparations in progress

Experimental design The experiments were laid out in a randomized complete block design with six treatments replicated three times. The treatments consisted of; TREATMENTS Chemical nameTRT1TRT2TRT3TRT4TRT5TRT6 50 % of Recommended company rate Recommended company rate 125% of Recommend ed company rate Standard check Local checkUntreated control The varieties used were Basmati 370 and Basmati 217

Data at harvest; Number of tillers per hill Number of productive tillers/hill Number of grains/panicle Number of empty grains/panicle 1000 grain weight at 14% MC

RESULTS Rice blast disease incidence/severity and effect on some yield parameters

Effect on grain yield

Conclusion From the results; It is evident that the new fungicides have an effect on rice blast. Severity in plots sprayed with the new fungicides were not significantly different from those sprayed with Bavistin (standard check) and Goldazim (local check). Similar trend was observed on the filled grains, 1000 grain weight and biomass per plant. The fungicides have therefore been recommended for registration by PCPB for use by farmers in the control of rice blast.

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