the Symposium on Wheats for More Tropical Environments - cimmyt

204Chemical Control ofWheat Diseases in <strong>the</strong> PhilippinesD.B. Lapis, Institute for Plant Breeding, University of <strong>the</strong>Philippines, Los BaAos, PhilippinesAbstractCommercial production of wheat has only been attempted in <strong>the</strong> Philippines in<strong>the</strong> 1980s. This has been triggered by <strong>the</strong> release of two varieties, Trigo 1 andTrigo 2. These cultivars have agronomic adaptation to <strong>the</strong> environmentalconditions of <strong>the</strong> country, but lack resistance to <strong>the</strong> major diseases. As <strong>the</strong>development of resistant cultivars takes time, chemicals have been evaluatedfordisease control when applied asfoliar sprays,forfrequency and rates ofapplicationfor leafspot control, as well asfor seed treatmentsfor protectingagainst and eradicating soil and seed-borne pathogens. Foliar sprays testedunder nursery conditions have shown that Tilt 250 EC is <strong>the</strong> most effectivechemicalfor controlling helminthosporium leaf spot. Some chemicals have alsoshown promise as protectants and eradicants ofseed-borne diseases; Homai.Vitavax-thiram, Vitavax-captan and Arasan are effective against Sclerotiumrolfsii. Rhizoctonia solani and FUsarium moniliforme. as well asfor seed-bornefungi.Although <strong>the</strong> Philippines has a longhistory of wheat cultivation, datingback as early as 1664, recentcommercial production has only beenattempted in <strong>the</strong> 19808. This attemptwas triggered by <strong>the</strong> release by <strong>the</strong>Philippine Seed Board of two wheatvarieties. UPLWI and UPLW2 (Trigo 1and Trigo 2). with good adaptation to<strong>the</strong> environmental conditions of <strong>the</strong>country. Unluckily. <strong>the</strong> two wheatvarieties lack resistance to majordiseases present in <strong>the</strong> Philippines.Faced with this situation. and realizingthat <strong>the</strong> development of resistantcultivars would be <strong>the</strong> most logical andeconomical approach to disease control,a breeding program has been begun.Since <strong>the</strong> development of resistantcultivars takes time. as an emergencymeasure chemicals were evaluated fordisease control in 1984. They weretested for use as foliar sprays and forfrequency and rates of application forleaf spot control. as well as for seedtreatments for protecting against anderadicating soil and seed-bornepathogens.Foliar sprays of chemicals undernursery conditions. using <strong>the</strong> microplottechnique. showed that <strong>the</strong> fungicidesCaltan F. Manzate D. Manzate 200.Orthocide 50 WP and Vinicur. at <strong>the</strong>irrecommended rates. and Tilt 250 EC. at0.4 and 0.6 ltlha formulated product(FP). were effective both as protectantsand as eradicants. compared with <strong>the</strong>control. Among <strong>the</strong>se chemicals. itappeared that Tilt 250 EC at <strong>the</strong> rate of0.6 ltlha FP was <strong>the</strong> most effectivechemical for controlling helminthosporiumleaf spot, with 24 and 14 meanlesion counts. as a protectant and aneradicant. respectively (Table 1). Thiswas fur<strong>the</strong>r corroborated with fieldexperiments; Tilt 250 EC at 0.6 It/ha FPgave 65% control and a yield of 1.5 tlhaversus <strong>the</strong> yield of <strong>the</strong> control at 0.9tlha (Table 2).