Effect of Fungicide Application on the Management of Avocado Branch Canker (Formerly Dothiorella Canker) in California


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Twizeyimana M., Mcdonald V., Mayorquin J. S. , Wang D. H. , Na F., Akgul D. S. , ...Daha Fazla

PLANT DISEASE, cilt.97, ss.897-902, 2013 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 97
  • Basım Tarihi: 2013
  • Doi Numarası: 10.1094/pdis-06-12-0518-re
  • Dergi Adı: PLANT DISEASE
  • Sayfa Sayıları: ss.897-902

Özet

Members of the Botryosphaeriaceae family have been associated with

branch cankers of avocado trees (Persea americana) in California.

Canker infections are initiated by spores entering the host plant

through fresh wounds such as pruning wounds. With high-density

planting becoming more common in the California avocado industry,

more intensive pruning may increase the occurrence of branch canker.

The objective of this study was to evaluate the preventive ability of

some commercial fungicides belonging to different chemical families

against fungal pathogens associated with avocado branch canker. Initially,

12 fungicides were tested in vitro for their effect on the inhibition

of mycelial growth of three isolates of Dothiorella iberica and

isolates (five per species) of Neofusicoccum australe, N. luteum, N.

parvum, and Phomopsis sp. Subsequently, azoxystrobin, fludioxonil,

metconazole, and pyraclostrobin, selected because of their low effective concentrations that reduce 50% of mycelial growth (EC50 values),

and myclobutanil, selected for its high EC50 value, were tested in two

field experiments. Azoxystrobin and fludioxonil were used in a premix

with propiconazole and cyprodinil, respectively, in field trials. Significant

differences (P < 0.05) were observed among fungicides in field

trials. Azoxystrobin + propiconazole had the highest percent inhibition

at 52 and 62% (internal lesion length) in trial 1 and trial 2, respectively,

although this level of inhibition was not significantly different from

that of metconazole. A significant correlation (r = 0.51, P < 0.05) was

observed between internal lesion length data in the field experiment

and EC50 data from in vitro fungicide screening. Application of

azoxystrobin + propiconazole and metconazole can play a key role in

protecting Californian avocado against fungi causing avocado branch

canker.

Members of the Botryosphaeriaceae family have been associated with branch cankers of avocado trees (Persea americana) in California. Canker infections are initiated by spores entering the host plant through fresh wounds such as pruning wounds. With high-density planting becoming more common in the California avocado industry, more intensive pruning may increase the occurrence of branch canker. The objective of this study was to evaluate the preventive ability of some commercial fungicides belonging to different chemical families against fungal pathogens associated with avocado branch canker. Initially, 12 fungicides were tested in vitro for their effect on the inhibition of mycelial growth of three isolates of Dothiorella iberica and isolates (five per species) of Neofusicoccum australe, N. luteum, N. parvum, and Phomopsis sp. Subsequently, azoxystrobin, fludioxonil, metconazole, and pyraclostrobin, selected because of their low effecfive concentrations that reduce 50% of mycelial growth (EC50 values), and myclobutanil, selected for its high EC50 value, were tested in two field experiments. Azoxystrobin and fludioxonil were used in a premix with propiconazole and cyprodinil, respectively, in field trials. Significant differences (P < 0.05) were observed among fungicides in field trials. Azoxystrobin + propiconazole had the highest percent inhibition at 52 and 62% (internal lesion length) in trial 1 and trial 2, respectively, although this level of inhibition was not significantly different from that of metconazole. A significant correlation (r = 0.51, P < 0.05) was observed between internal lesion length data in the field experiment and EC50 data from in vitro fungicide screening. Application of azoxystrobin + propiconazole and metconazole can play a key role in protecting Californian avocado against fungi causing avocado branch canker.