Effects of wounding, humidity, temperature, and inoculum concentrations on the severity of corky dry rot caused by Fusarium semitectum in melon fruits

h p://www.uem.b /ac a ISSN p in ed: 1679-9275 ISSN on-line: 1807-8621 Ac a Scien ia um Doi: 10.4025/ac asciag on. 36i3.17656 Ac a Scien ia um. Ag onomy Ma ingá, . 36, n. 3, p. 281-289, July-Sep ., 2014 E ec s o wounding, humidi y, empe a u e, and inoculum concen a ions on he se e i y o co ky d y o caused by Fusa ium semi ec um in melon ui s Michelle Ja delina de Oli ei a1, Delson La anjei a1, Ma cos Paz Sa ai a Câma a1, F ancisco Fe az La anjei a2, Josep A mengol3 and Sami Jo ge Miche e 1 1Depa amen o de Ag onomia, Uni e sidade Fede al Ru al de Pe nambuco, Rua Dom Manoel de Medei os, s/n, 52171-900, Reci e, Pe nambuco, B azil. 2Labo a ó io de Fi opa ologia, Emb apa Mandioca e F u icul u a, C uz das Almas, Bahia, B azil. 3Ins i u o Ag o o es al Medi e áneo, Uni e sidad Poli écnica de Valencia, Valencia, Spain. *Au ho o co espondence. E-mail: [email p o ec ed] ABSTRACT. Co ky d y o , caused by Fusa ium semi ec um, is he main pos ha es disease o melons in B azil. This s udy in es iga ed he e ec s o wounding, humidi y, empe a u e, and inoculum concen a ion on he se e i y o co ky d y o unde con olled condi ions. Can aloupe and honeydew melon ypes we e inocula ed by sp aying conidial suspensions o h ee F. semi ec um isola es. In all expe imen s, he es ed F. semi ec um isola es did no di e in ela ion o disease se e i y, bu , he can aloupe melon showed highe le els o se e i y. No lesions appea ed on ui s ha lacked wounds, and inc easing wound age educed lesion se e i y. Melons ha we e inocula ed wi h F. semi ec um de eloped symp oms ega dless o he p esence o absence o a mois chambe a he pos -inocula ion s age, bu he lesions we e la ge unde mois chambe condi ions. The e we e no symp oms a 10°C, bu a empe a u e inc ease om 15 o 25°C esul ed in a disease se e i y inc ease. The la ges lesions we e obse ed when bo h melon ypes we e inocula ed wi h a concen a ion o 106 conidia mL-1, bu e en he lowes concen a ion (101 conidia mL-1) was su icien o causing lesions. Inju y educ ion and/o he accele a ion o melon healing, as well as en i onmen al a iable con ol and a educ ion o inoculum sou ces, a e essen ial o educing co ky d y o se e i y. Keywo ds: Cucumis melo, ui o , pos ha es pa hology, epidemiology. E ei o de e imen o, umidade, empe a u a e concen ação de inóculo na se e idade da pod idão seca causada po Fusa ium semi ec um em u os de melão RESUMO. A pod idão seca causada po Fusa ium semi ec um é a p incipal doença pós-colhei a do melão no B asil. Es e es udo in es igou o e ei o de e imen o, umidade, empe a u a e concen ação de inóculo na se e idade da pod idão seca em condições con oladas. F u os de melão dos ipos can aloupe e honeydew o am inoculados po meio da pul e ização de suspensão de conídios de ês isolados de F. semi ec um, inoculados sepa adamen e. Em odos os expe imen os os isolados de F. semi ec um es ados não di e i am em elação à se e idade da doença, po ém, a a iedade can aloupe ap esen ou maio es ní eis de se e idade da doença. Não hou e lesões em u os sem e imen o e o inc emen o na idade do e imen o eduziu a se e idade. Melões inoculados com F. semi ec um desen ol e am sin omas independen emen e de câma a úmida pós-inoculação, mas as lesões o am maio es em condições de câma a úmida. Não hou e sin omas a 10°C, mas o aumen o da empe a u a de 15 pa a 25°C esul ou num inc emen o da se e idade da doença. As maio es lesões o am obse adas na concen ação de inóculo de 106 conídios mL-1 nos dois ipos de melão, mas a meno concen ação (101 conídios mL-1) oi su icien e pa a causa leões. A diminuição de injú ias nos u os de melão e/ou a acele ação da cica ização, bem como o con ole das a iá eis ambien ais e a edução das on es de inóculo são essenciais pa a edução da se e idade da pod idão seca. Pala as-cha e: Cucumis melo, pod idão do u o, pa ologia pós-colhei a, epidemiologia. In oduc ion Melon (Cucumis melo L.) is an economically impo an c op in B azil, whe e i ep esen s he second la ges B azilian esh ui expo , and places he coun y among he op en melon expo e s in he wo ld. The no heas e n egion o B azil accoun s o 85% o he coun y’s melon p oduc ion and co e s app oxima ely 14,900 ha. The main p oducing a eas a e loca ed in he S a es o Rio G ande do No e, wi h 7,582 ha esul ing in an annual p oduc ion o 201,250 on, and Cea á, wi h 4,304 ha esul ing in an annual p oduc ion o 124,157 on (AGRIANUAL, 2012). Pos ha es o s cause se e e losses in B azilian melon p oduc ion. I is es ima ed ha be ween 10 o 282 Oli ei a e al. Ac a Scien ia um. Ag onomy Ma ingá, . 36, n. 3, p. 281-289, July-Sep ., 2014 30% o pos ha es losses a e due o co ky d y o , which is caused by Fusa ium semi ec um Be k. & Ra enel. (Synonym: Fusa ium inca na um (Robe ge) Sacc., Fusa ium pallido oseum (Cooke) Sacc.). This disease was de ec ed in 1999 in melons om Rio G ande do No e S a e, and i s incidence has p og essi ely inc eased (TERAO e al., 2008). Co ky d y o is a majo cause o can aloupe melon losses (C. melo a . can aloupensis Naud.) (BRUTON, 1995; BRUTON; DUTHIE, 1996; CARTER, 1979; MCGOVERN, 1994), bu he o also a ec s honeydews (C. melo a . inodo us H. Jacq.) and se e al o he melon a ie ies (BRUTON, 1995; BRUTON e al., 1998; BRUTON; DUTHIE, 1996; DIAS; TERAO, 2006). Disease symp oms may appea in he ield (a he p eha es phase), close o ui ma u i y, o in he pos ha es phase. Lesions a e a iable in leng h, om 2 mm o 8 cm, and hey also a y in dep h, om 2 mm o 3 cm. They a e especially p e alen on he s ems and he blossom ends o he ui , bu hey can occu on any a ea o he ui . E idence o his disease consis s o a hickening o he ne and/o de elopmen o co ky issue along he ein ac s. C acks a e o en ound in la ge lesions. Unde high humidi y, a ligh pink o beige mycelium appea s on he ind su ace immedia ely abo e he co ky lesion. A ec ed zones will i s appea as small whi e spongy a eas benea h he ind. In ime, hese a eas will u n da k b own, d y, and mealy. In la ge lesions, he b own issue is su ounded by a whi e, mois , spongy issue ha ex ends in o he lesh o he ui . A dis inc ma gin sepa a es he diseased and heal hy issues, and he lesion can easily be emo ed in ac om he lesh (BRUTON; DUTHIE, 1996; CARTER, 1979; MCGOVERN, 1994). Con olling co ky d y o is e y di icul . The e o e, i is essen ial o adop in eg a ed managemen s a egies. The e is no known esis ance o co ky d y o (MCGRATH, 2004). P eha es ungicide applica ions ha e been somewha ine ec i e because o he di icul y o eaching su icien ui co e age. A emp s a pos ha es con ol ha e also yielded e a ic esul s. Using ungicides in combina ion wi h a ho -wa e ea men (57°C o 1 min.) has p o ided some success in con olling he disease, bu s udy esul s on hese combined ea men s a e inconclusi e. Wounding a oidance du ing ha es and packing, p ope s o age and ansi empe a u es, and p omp handling o melons upon a i al a he ma ke can p o ide some p o ec ion agains pos ha es decay (BRUTON, 1995; BRUTON; DUTHIE, 1996). Mo e ecen ly, he con ol o co ky d y o h ough he ac i a ion o sys emic esis ance (BI e al., 2010; GE e al., 2008; GONDIM e al., 2008) and he use o e hylene inhibi o s (ALVES e al., 2005; TERAO e al., 2009) ha e been in es iga ed, bu wi h highly a iable esul s. B azilian melons ha a e expo ed, pa icula ly hose ha a e des ined o he Eu opean Union coun ies, a e equi ed o be o high quali y, undamaged, and phy opa hogen- ee. Co ky d y o ep esen s a se ious obs acle o he comme cializa ion o melons, pa icula ly as o eign commodi ies (GONDIM e al., 2008). Melon ui s ha a e a ec ed by co ky d y o a e no ma ke able. Al hough a wo king knowledge abou he condi ions ha a o disease de elopmen is essen ial o imp o e disease managemen s a egies, li le in o ma ion is a ailable on he epidemiology o co ky d y o in melon (BRUTON; DUTHIE, 1996). The p esen s udy was unde aken o e alua e he e ec s o wounding, humidi y, empe a u e, and inoculum concen a ions o F. semi ec um on he se e i y o co ky d y o in melons unde con olled condi ions. Ma e ial and me hods Fungal isola es Th ee single-spo e F. semi ec um isola es (CMM- 589, CMM-685 and CMM-687) we e used o all expe imen s. The isola es we e ob ained om melon ui s ha we e exhibi ing symp oms o co ky d y o in h ee g owing a eas o no heas e n B azil, which a e loca ed in he ag icul u al a ea o Mosso ó (Rio G ande do No e S a e). The isola es we e mo phologically iden i ied as F. semi ec um a e being g own on po a o dex ose aga (PDA) (Acumedia Co., Lansing, MI, USA) and Spezielle Näh s o a me aga (SNA) cul u e media (LESLIE; SUMMERELL, 2006) o 10 days a 25ºC wi h a 12-h pho ope iod. Addi ionally, pa o he ansla ion elonga ion ac o 1-alpha (EF1-α) gene was used o con i m he iden i y o his Fusa ium species h ough a BLAST DNA sequence da abase sea ch (h p://isola e. usa iumdb.o g). A ep esen a i e sequence o he DNA egion o s udy om isola e CMM-687 was deposi ed a GenBank (JQ004800). This sequence had a 99.06% simila i y wi h he sequence o F. semi ec um (= F. pallido oseum) (NRRL 31160). All expe imen s we e conduc ed wice. P io o he expe imen s, he isola es we e cul i a ed in Pe i dishes con aining PDA and incuba ed a 25 ± 2ºC wi h a 12-h pho ope iod using luo escen ligh (40 μmol m-2 s -1) o 10 days. Epidemiology co ky d y o melon ui s 283 Ac a Scien ia um. Ag onomy Ma ingá, . 36, n. 3, p. 281-289, July-Sep ., 2014 Fungal inoculum was p epa ed by gen ly insing he aga su ace wi h s e ile wa e and, hen, il e ing he esul ing mycelium and conidia suspensions h ough ou laye s o cheeseclo h. The conidia suspensions we e coun ed wi h a hemocy ome e and adjus ed by adding s e ile ap wa e . Be o e inocula ion, Tween 20 (0.05%) was added o he inoculum. The ge mina ion o each ba ch o inoculum was measu ed p io o inocula ion o ensu e conidia iabili y. Suspensions wi h less han 90% conidia ge mina ion we e disca ded. F ui s Melon ui s om can aloupe (c . To eon) and honeydew (c . O ange Flesh) ypes we e ha es ed om a comme cial plan a ion a he ipening s age and selec ed o uni o mi y o size, ipeness, and absence o inju ies. These ui s we e used in all he expe imen s. Be o e inocula ion, he ui s we e ca e ully washed, su ace-disin es ed by imme sion in a 1.5% NaOCl solu ion in s e ile wa e o 5 min., insed wice wi h s e ile dis illed wa e , and allowed o ai d y on a labo a o y bench. Wounding e ec s Wounded and non-wounded ui s we e used in his expe imen . To make wounded ui s, he epide mis was punc u ed a ou equidis an poin s. Fi e wounds (3 mm deep and 0.8 mm wide) we e made a each poin wi h a s e ile needle p io o inocula ion. Immedia ely a e wounding, ui s we e sp ayed wi h a conidial suspension (2 mL pe ui , wi h 106 conidia mL-1 in s e ile wa e plus Tween 20 (0.05%)) o each F. semi ec um isola e. Con ol ui s we e inocula ed wi h s e ile wa e plus Tween 20 (0.05%). The inocula ed and con ol ui s we e placed on plas ic mois chambe s (50 x 30 x 20 cm). To encou age high humidi y, he bo om o each mois chambe was lined wi h a dis illed wa e -soaked pape owels. T ays we e kep in g ow h chambe s a 25 ± 2ºC unde luo escen ligh (12-h pho ope iod, 40 μmol m-2 s -1). F ui s we e emo ed om he mois chambe s a e 48h o incuba ion and we e kep a he same empe a u e o an addi ional 3-day pe iod. The lesion size (mm2) a each inocula ed poin was measu ed 5 days a e inocula ion by measu ing i s leng h and wid h in wo pe pendicula di ec ions. The ull ac o ial combina ion o he ea men s (3 x 2 x 2), which a e ep esen ed by h ee F. semi ec um isola es, wo melon a ie ies and wounded and non-wounded ui s, was a anged in a comple ely andomized design wi h ou eplica es pe ea men and i e ui s pe eplica e. Wound age e ec s Wounded ui s we e sp ayed wi h a conidial suspension (2 mL pe ui ; 106 conidia mL-1 in s e ile wa e plus Tween 20 (0.05%)) o each F. semi ec um isola e. The inocula ions we e ca ied ou immedia ely a e wounding, and 12 and 24h a e . The con ol ui s we e inocula ed wi h s e ile wa e and Tween 20 (0.05%). The incuba ion condi ions and disease e alua ion we e ca ied ou he same way as desc ibed in he expe imen on wounding e ec s. The ull ac o ial combina ion o ea men s (3 x 2 x 3), which ep esen ed h ee F. semi ec um isola es, wo melon a ie ies and h ee wound ages, was a anged in a comple ely andomized design wi h ou eplica es pe ea men and i e ui s pe eplica e. Humidi y e ec s Wounded ui s we e inocula ed wi h F. semi ec um isola es by sp aying (2 mL pe ui ; 106 conidia mL-1 in s e ile wa e plus Tween 20 (0.05%)) he ui s immedia ely a e wounding. Con ol ui s we e inocula ed wi h s e ile wa e and Tween 20 (0.05%). The inocula ed and con ol ui s we e subjec ed o wo di e en condi ions: incuba ion in mois chambe s o incuba ion wi hou mois chambe s, bo h o 48h. The incuba ion condi ions, expe imen al design and disease e alua ion we e he same as desc ibed o he wounding e ec s expe imen . Tempe a u e e ec s F ui s we e wounded and inocula ed wi h F. semi ec um isola es by sp aying (2 mL pe ui ; 106 conidia mL-1 in s e ile wa e and Tween 20 (0.05%)) he ui s immedia ely a e wounding. The con ol ui s we e inocula ed wi h s e ile wa e and Tween 20 (0.05%). The inocula ed and con ol ui s we e placed in mois chambe s and, hen, incuba ed in g ow h chambe s a 5, 10, 15, 20, 25, 30 and 35°C unde luo escen ligh (12-h pho ope iod, 40 μmol m-2 s -1). A e 48h o incuba ion, he ui s we e emo ed om he mois chambe s and le o an addi ional 3-day pe iod a he same empe a u es. The disease e alua ion was pe o med as desc ibed o he wounding e ec expe imen . The ull ac o ial combina ion o ea men s (3 x 2 x 7), which ep esen ed h ee F. semi ec um isola es, wo melon a ie ies and se en empe a u es, was a anged in a comple ely andomized design wi h ou eplica es pe ea men and i e ui s pe eplica e. Inoculum concen a ion e ec s F ui s we e inocula ed by sp aying hem wi h a conidial suspension (2 mL pe ui ) o each F. semi ec um isola e immedia ely a e wounding, 284 Oli ei a e al. Ac a Scien ia um. Ag onomy Ma ingá, . 36, n. 3, p. 281-289, July-Sep ., 2014 a six di e en concen a ions (101, 102, 103, 104, 105, o 106 conidia mL-1 in s e ile wa e and Tween 20 (0.05%)). Con ol ui s we e inocula ed wi h s e ile wa e and Tween 20 (0.05%). The incuba ion condi ions and disease e alua ion we e he same as hose desc ibed in he expe imen on wounding e ec s. The ull ac o ial combina ion o ea men s (3 x 2 x 6), which ep esen ed h ee F. semi ec um isola es, wo melon a ie ies and six inoculum concen a ions, was a anged in a comple ely andomized design wi h ou eplica es pe ea men and i e ui s pe eplica e. S a is ical analysis Analyses o a iance (ANOVAs) we e conduc ed wi h da a ha we e ob ained om he expe imen s on he e ec s o wounding, wound age, humidi y, empe a u e, and inoculum concen a ion. In all cases, ANOVA analyses indica ed ha he da a be ween he wo epe i ions we e simila (p > 0.05), and hus he da a om all a iables in bo h expe imen s we e combined. Fi s , he da a om each expe imen we e subjec ed o h ee-way ANOVA analyses. In all expe imen s, he F. semi ec um isola es did no di e signi ican ly (p > 0.05) among one ano he in ela ion o he le els o disease se e i y ha hey could induce, and signi ican in e ac ions wi h melon ypes we e no ound. On he o he hand, signi ican di e ences in disease le els be ween he di e en melon ypes we e ound in all expe imen s. The e o e, only he isola es’ a e ages wi hin each melon ype we e conside ed ac oss all s a is ical analyses. The wounding and humidi y ea men s we e compa ed using S uden ’s - es (p ≤ 0.05), whe eas he wound age ea men s we e compa ed using Fishe ’s LSD es (p  0.05). These s a is ical analyses we e pe o med wi h S a is ix . 9.0 so wa e (Analy ical So wa e, Tallahassee, FL, USA). Da a om he empe a u e and inoculum concen a ion expe imen s we e analyzed by i ing linea and nonlinea eg ession models wi h he aid o TableCu e 2D . 5.01 so wa e (SYSTAT So wa e Inc., Chicago, IL, USA). The bes - i cu es showing co ky d y o se e i y (lesion size) we e selec ed on he basis o he coe icien o de e mina ion (R2) and he mean squa ed esidue. The signi icance o he eg essions and hei pa ame e s we e e i ied by F es (p ≤ 0.05). Resul s and discussion This is he i s s udy in which he e ec s o wounding, humidi y, empe a u e, and F. semi ec um inoculum concen a ion ha e been de e mined wi h ela ion o he se e i y o co ky d y o in melon ui s. The h ee F. semi ec um isola es did no di e signi ican ly (p > 0.05) among hemsel es in ela ion o he le els o induced disease se e i y in any o he expe imen s. High le els o in aspeci ic a iabili y exis wi hin F. semi ec um isola es ha a e ob ained om a single hos , such as co on (ABD- ELSALAM e al., 2003), al al a (ZACCARDELLI e al., 2006) and ed- leshed d agon ui (HAWA e al., 2010). In ou case, he occu ence F. semi ec um isola es wi h simila i ulence le els in melon ui s may be due o he low numbe o isola es because hey all came om he same ag icul u al egion. Rega ding he e ec s o di e en melon a ie ies, he can aloupe showed signi ican ly (p  0.05) highe le els o co ky d y o se e i y in all expe imen s han hose o he honeydew (Figu es 1A, B, C, 2 and 3). The suscep ibili y di e ence be ween hese melon a ie ies may be associa ed wi h he s uc u al cha ac e is ics o he ui epide mis. Honeydew melons ha e a conside ably hicke epide mis and no ne in compa ison o can aloupes. The memb ane in eg i y o he hypode mal issue in melon ui s appea s o be highly co ela ed o hei shel li e (LESTER, 1988). Wounding e ec s The e was no appea ance o symp oms in melon ui s when inocula ions we e pe o med wi hou wounding (Figu e 1A), indica ing ha he pa hogen is unable o pene a e he ui di ec ly. F ui inju ies we e essen ial o ini ia ing he in ec ion p ocess, which acili a ed pa hogen pene a ion. In addi ion, inju ed issue inc eases he me abolic ac i i y o inju ed cells (GUZMÁN e al., 1999), leading o an ele a ed espi a ion a e, induc ion o e hylene syn hesis, and inc eased wa e loss, esul ing in accele a ed ui de e io a ion (ADASKAVEG e al., 2002; JACOMINO e al., 2004). In he ield, melon ui s can su e a ious o ms o inju ies du ing c op managemen , such as when ui s a e d agged on he g ound, h ough in e ac ions wi h cu ing ins umen s o small s ones, o by he ac i i y o insec s, which end o sc ape he su ace, lea e pi s, o pene a e he ui s in hei sea ch o ood (VIANA e al., 2001). I is also wo h no ing ha he pene a ion o melon ui s by F. semi ec um can also occu h ough na u al openings, including len icels o c acks in he epide mis ha a e associa ed wi h ne de elopmen (BRUTON e al., 1998). Epidemiology co ky d y o melon ui s 285 Ac a Scien ia um. Ag onomy Ma ingá, . 36, n. 3, p. 281-289, July-Sep ., 2014 A aB aA bA aB 0 100 200 300 400 500 600 Non Wounded Wounded Wounding Lesion size (mm 2 ) Can aloupe Hone yde w B aC aB aA bA bB bC 0 100 200 300 400 500 600 01224 Wound age (hou s) Lesion size (mm 2 ) Can aloupe Honeydew C aA aB bB bA 0 100 200 300 400 500 600 Wi hou Wi h Humid chambe Lesion size (mm 2 ) Can aloupe Honeydew Figu e 1. E ec o wounding (A), wound age (B) and humidi y (C) on co ky d y o se e i y (as indica ed by lesion size) in can aloupe (c . To eon) and honeydew (c . O ange Flesh) melon ypes inocula ed wi h Fusa ium semi ec um. Values a e p esen ed as he means om wo independen expe imen s. Values ollowed by he same lowe -case le e o melon ypes and capi al le e o wounding, wound ages and humidi y condi ions do no di e signi ican ly acco ding o Fishe ’s LSD es (p  0.05). Wound age e ec s F ui wound ages signi ican ly in luenced he se e i y o co ky d y o . This ac o was also ound o educe he lesion size wi h inc easing wound age (Figu e 1B). In bo h melon a ie ies, he lesions we e la ge in ui s ha we e immedia ely inocula ed a e wounding han in he o he ea men s. This may be a consequence o inc eased wa e a ailabili y in he o m o exuda es ha we e eleased soon a e he inju y. The healing p ocess may also ha e in luenced he disease se e i y because he can aloupe p oduces lignin and sube in du ing issue healing, deposi ing hese compounds on he walls o inju ed cells o o m a lesion pe ide m (JACOMINO e al., 2004), which may p o ide a s uc u al esis ance mechanism agains in ec ion. Ano he aspec o conside is ha esh wounds gene ally accele a e he a e o espi a ion and e hylene syn hesis because o he ensuing high me abolic ac i i y o cell wounds ha occu wi hin minu es a e cu ing (GUZMÁN e al., 1999). The lowe se e i y ha was obse ed in olde wounds can also be a ibu ed o an accumula ion o phy oalexins and pa hogenesis- ela ed (PR) p o eins in esponse o mechanical inju y, which can inhibi pa hogen ac ions. Phy oalexins a e p oduced by heal hy cells nea he inju y si e in esponse o subs ances ha a e p oduced in damaged cells, which accumula e and can p o ide esis ance o he co ky d y o ungus (ADASKAVEG e al., 2002). Humidi y e ec s The melon ui s ha we e inocula ed wi h F. semi ec um de eloped symp oms o co ky d y o ega dless o he p esence o absence o a mois chambe (Figu e 1C), indica ing ha ee wa e was no needed, a leas no in he o m o condensa ion on he ui su ace, o spo e ge mina ion and hos pene a ion. This esul con as s wi h he obse a ion ha he p esence o a ilm o wa e is essen ial o F. semi ec um spo e ge mina ion (PEREZ; VIDAL, 2002). The occu ence o in ec ions by his pa hogen in he absence o a mois chambe indica es ha he me e mois u e ha is associa ed wi h exuda es ha we e eleased by he ui a e wounding was su icien o s a he p ocesses ha we e in ol ed in pa hogenesis, as also ound in yellow melon ui s inocula ed wi h he bac e ium Acido o ax a enae subsp. ci ulli (Schaad e al.) Willems e al. (SILVEIRA e al., 2004). Mo eo e , i is impo an o conside ha F. semi ec um is esis an o low humidi y condi ions and can emain in he ield o long pe iods unde condi ions o ex eme d ough (BADGER, 1965). Co ky d y o lesions we e highe in ui s ha we e subjec ed o a mois chambe (Figu e 1C), indica ing ha high mois u e s imula es he in ec ion p ocess by F. semi ec um and/o inc eases hos suscep ibili y, in luencing he a e o disease p og ession and demons a ing he g ea es se e i y, as has been obse ed p e iously in banana ui s 286 Oli ei a e al. Ac a Scien ia um. Ag onomy Ma ingá, . 36, n. 3, p. 281-289, July-Sep ., 2014 a e ha es (PEREZ; VIDAL, 2002). The mois u e loss o esh p oduce is de e mined by ela i e humidi y. High le els o humidi y help o main ain ui u gidi y and o educe wa e loss bu may also be conduci e o disease de elopmen (ADASKAVEG e al., 2002). In he melon- p oducing a eas o no heas e n B azilian, he e is no high humidi y occu ence du ing he day. Howe e , he e a e se e al sho pe iods o we ness a nigh . This dampness may be su icien o s imula e he F. semi ec um in ec ion p ocess, as also happens in o he pa hosys ems in semi-a id egions (ROTEM, 1978). The dew o ma ion ha occu s as a esul o di e ences be ween day and nigh empe a u es also p o ides pe iods o we ness in he ea ly hou s o he day. Fu he mo e, in e up ions in pe iods o we ness by d y days may be o se by he mois u e ha is added by some cul u al p ac ices ha a e used by no heas e n B azilian melon p oduce s, such as d ip i iga ion, plas ic mulch, and ow co e s made om ag o ex iles. Tempe a u e e ec s The empe a u e signi ican ly in luenced he se e i y o co ky d y o in melon ui s. In gene al, he disease se e i y inc eased as empe a u e inc eased om 15 o 25°C, whe eas lesions we e smalle when he empe a u e was highe han 25ºC (Figu e 2). The e we e no symp oms a 10ºC (Figu e 2), con i ming obse a ions abou he impo ance o e ige a ing ui s a ha empe a u e o con ol co ky d y o . Howe e , e ige a ion is no le hal o F. semi ec um because he disease begins o de elop no mally again a e he ui s a e emo ed om he cold (TERAO e al., 2006). In addi ion o in luencing ui me abolism, he empe a u es may also possibly a ec pa hogen me abolism and he kine ics o enzymes ha a e in ol ed in he in ec ion p ocess, which inc ease o educe ac i i y depending on he p e ailing condi ions, which, in u n, a ec disease de elopmen (ADASKAVEG e al., 2002). The logis ic model wi h an asymme ic powe peak (Figu e 2) p o ided excellen i cu es o desc ibe he p og ess and se e i y o co ky d y o wi h espec o he empe a u e, wi h coe icien s o de e mina ion (R2) o 99.9 and 98.6% o can aloupe and honeydew melon, espec i ely. The chosen model had ou pa ame e s (a, b, c, d), and he i s wo pa ame e s a e o g ea biological in e es because hey e lec he maximum es ima ed lesion size (a) and he empe a u e a which he maximum lesion size occu ed (b). The can aloupe displayed a maximum es ima ed lesion size (421.6 mm2) ha was signi ican ly (p ≤ 0.05) la ge han in he honeydew (254.9 mm2), when he eg ession pa ame e was compa ed by - es using he con idence in e al. On he o he hand, he wo melon a ie ies did no di e signi ican ly (p  0.05) in iew o he op imum empe a u e o he disease, o which he es ima ed alues we e 23.0 and 23.9°C o he can aloupe and honeydew, espec i ely (Figu e 2). Figu e 2. E ec o empe a u e on co ky d y o se e i y (lesion size) in ui s o can aloupe (c . To eon) and honeydew (c . O ange Flesh) melon ypes inocula ed wi h Fusa ium semi ec um. Values a e p esen ed as he means om wo independen expe imen s. Tempe a u es and disease se e i y we e ela ed by he nonlinea eg ession analysis using he logis ic powe peak model, shown a he base o he g aphs. The op imum empe a u es ha we e es ima ed o he de elopmen o co ky d y o in his s udy we e lowe han 30°C, which was p e iously conside ed o be mo e a o able o disease de elopmen in melon ui s (DIAS; TERAO, 2006). In banana ui s, highe c own o se e i y caused by F. semi ec um was obse ed o occu a empe a u es be ween 25 and 27°C, whe eas he disease de elopmen was s ongly inhibi ed below 15°C, and no symp oms we e obse ed a 38°C (PEREZ; VIDAL, 2002). Melon ui s unde go p e- cooling be o e expo o lowe hei empe a u e o 10-15°C, and his ac ion could be conside ed o be an e icien con ol o co ky d y o a pos ha es . Howe e , he anspo ucks ha se e he domes ic B azilian ma ke lack e ige a ion, as do he supe ma ke s and/o ou doo ma ke s, which a o he incidence o co ky d y o . Inoculum concen a ion e ec s The inoculum concen a ion o F. semi ec um signi ican ly in luenced he se e i y o co ky d y o in melon ui s, and lesion sizes inc eased wi h Can aloupe R² = 99.9% a = 421.6 b = 23.0 c = 1.56 d = 10.7 Honeydew R² = 98.6% a = 254.9 b = 23.9 c = 2.05 d = 2.95 Epidemiology co ky d y o melon ui s 287 Ac a Scien ia um. Ag onomy Ma ingá, . 36, n. 3, p. 281-289, July-Sep ., 2014 inc easing inoculum concen a ions. La ge lesions we e obse ed a a concen a ion o 106 conidia mL-1 in bo h a ie ies o melons, bu e en he lowes concen a ion o inoculum (101 conidia mL-1) (Figu e 3) was su icien o causing lesions. The incidence o co ky d y o , e en wi h e y low inoculum concen a ions, indica es he high in ec ion po en ial o F. semi ec um spo es. Figu e 3. E ec o Fusa ium semi ec um inoculum concen a ions on co ky d y o se e i y (lesion size) in ui s o can aloupe (c . To eon) and honeydew (c . O ange Flesh) melon ypes. Values a e p esen ed as means om wo independen expe imen s. Inoculum concen a ion and disease se e i y we e ela ed by he single linea eg ession analysis. The single linea model (y = a + bx) p o ided excellen cu e i s o desc ibe he se e i y and p og ess o co ky d y o wi h espec o he inoculum concen a ions o F. semi ec um, wi h coe icien s o de e mina ion (R2) a 99.9 and 98.6% o can aloupe and honeydew melons, espec i ely (Figu e 3). The can aloupe expe ienced an es ima ed a e o lesion size p og ess (64.19 mm2 pe spo e concen a ion uni ) ha was signi ican ly (p  0.05) highe han he honeydew (34.32 mm2 pe spo e concen a ion uni ), when he eg ession pa ame e was compa ed by - es using he con idence in e al, once again demons a ing he high sensi i i y o he can aloupe o co ky d y o in compa ison o he honeydew. The inc eased se e i y o co ky d y o in melons wi h inc easing concen a ions o F. semi ec um inoculum highligh s he impo ance o educing he inoculum o minimize he isk o epidemics du ing he pos ha es pe iod, which may be achie ed by measu es ha educe he le el o inoculum in he ield, packing house and in s o age (DIAS; TERAO, 2006). Conside ing ha melon ui s ha a e le in he ield can be a sou ce o F. semi ec um inoculum, he elimina ion o in ec ed ui s du ing and a e each c op season is a e y impo an measu e o p e en ing he sp ead o disease. The single linea model (y = a + bx) p o ided excellen cu e i s o desc ibe he se e i y and p og ess o co ky d y o wi h espec o he inoculum concen a ions o F. semi ec um, wi h coe icien s o de e mina ion (R2) a 99.9 and 98.6% o can aloupe and honeydew melons, espec i ely (Figu e 3). The can aloupe expe ienced an es ima ed a e o lesion size p og ess (64.19 mm2 pe spo e concen a ion uni ) ha was signi ican ly (p  0.05) highe han he honeydew (34.32 mm2 pe spo e concen a ion uni ), when he eg ession pa ame e was compa ed by - es using he con idence in e al, once again demons a ing he high sensi i i y o he can aloupe o co ky d y o in compa ison o he honeydew. The inc eased se e i y o co ky d y o in melons wi h inc easing concen a ions o F. semi ec um inoculum highligh s he impo ance o educing he inoculum o minimize he isk o epidemics du ing he pos ha es pe iod, which may be achie ed by measu es ha educe he le el o inoculum in he ield, packing house and in s o age (DIAS; TERAO, 2006). Conside ing ha melon ui s ha a e le in he ield can be a sou ce o F. semi ec um inoculum, he elimina ion o in ec ed ui s du ing and a e each c op season is a e y impo an measu e o p e en ing he sp ead o disease. Conclusion Managemen p ac ices in ol ing he educ ion o inju y o ui s and/o he accele a ion o wound healing a e essen ial o educing he se e i y o co ky d y o in he pos ha es ea men o melon ui s. The con ol o en i onmen al a iables, such as humidi y and empe a u e, as well as he educ ion o inoculum sou ces can help o educe he se e i y o co ky d y o in melons. Re e ences ABD-ELSALAM, K. A.; SCHNIEDER, F.; ASRAN- AMAL, A.; KHALIL, M. S.; VERREET, J. A. In a-species genomic g oups in Fusa ium semi ec um and hei co ela ion wi h o igin and cul u al cha ac e is ics. Jou nal o Plan Diseases and P o ec ion, . 110, n. 6, p. 409-418, 2003. ADASKAVEG, J. E.; FÖRSTER, H.; SOMMER, N. F. P inciples o pos ha es pa hology and managemen o decays o edible ho icul u al c ops. In: KADER, A. (Ed.). Pos ha es echnology o ho icul u al c ops. 288 Oli ei a e al. Ac a Scien ia um. Ag onomy Ma ingá, . 36, n. 3, p. 281-289, July-Sep ., 2014 3 d ed. 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