Conventional and reduced-risk fungicides to control postharvest Diplodia and Phomopsis stem-end rot on lemons

CERIONI, LUCIANA; BENNASAR, PAULA B.; LAZARTE, DANIELA; SEPULVEDA, MILENA; SMILANICK, JOSEPH L.; RAMALLO, JAQUELINE; RAPISARDA, VIVIANA A.

SCIENTIA HORTICULTURAE

ELSEVIER SCIENCE BV

Año: 2017 vol. 225 p. 783 - 787

0304-4238

Stem-end-rot (SER), caused by Lasiodiplodia theobromae or Diaporthe citri, is an important postharvest disease inhumid and warm citrus growing areas, such as the Northwestern region of Argentina. The commercial control ofSER has been accomplished by applications of the systemic fungicide carbendazim (CARB). However, alternativechemicals for this fungicide are needed due to increasing restrictive regulations in overseas markets. The aim ofthis work was to evaluate the effectiveness of conventional and reduced-risk postharvest fungicides to controlSER. In vitro tests show that L. theobromae was more resistant to fungicides than D. citri. In trials using artificiallyinoculated lemons, SER caused by D. citri (Phomopsis SER) was controlled by the fungicides evaluated. Theconventional fungicides imazalil and thiabendazole (TBZ) were the most effective chemicals to control SERcaused by L. theobromae (Diplodia SER), while other fungicides, as fludioxanil, azoxystrobin, pyrimetanil andpropiconazole, were not effective. The best control of Diplodia SER was obtained by immersion for 60 s in2000 mg/L of TBZ at pH 5 and 20 °C. In this condition, TBZ-residue loading on lemons was 3.0 mg-L−1, whichdid not exceed the allowed maximum residue levels. TBZ applied in lemon commercial treatments is the bestoption to reduce SER caused by both pathogens. At this time, this is the unique suitable alternative to replaceCARB treatment in Argentinean packinghouses