Articles
PITTING ON KIWIFRUIT IN STORAGE CAUSED BY PHIALOPHORA SP
Skin pitting symptoms appear on fruits after 3 month of storage or more, usually they affect low percentage of fruits (2–5 %) and are widespread in most kiwifruit packing houses.
Strains identified as Phialophora sp. were isolated from almost all typical lesions.
Four main morphocultural profiles were described among them, one strain from each group was chosen as representative and submitted to mycological studies whose main results were pointing out high variability of this population and its ability to grow at 0°C. Sure specific identification was not possible, being the strains very near to P. malorum on the basis of some morphocultural characteristics but more similar to P. parasitica for other ones.
To assess actual role of Phialophora sp., fungicide treatments and wounds in disease progression, in 1994 harvested kiwifruit were artificially inoculated by spraying Phialophora spores on wounded and unwounded fruits, half of which also treated with vinclozolin.
Air dried kiwifruits were then CA-stored at – 0.5°C and 90% RH.
Results were recorded at the end of storage time and confirmed Phialophora sp. as the causal agent and the heavy influence of wounds on fungal settlement.
At the beginning of April 1995, fruits sprayed and wounded showed about 32% infected wounds when treated with vinclozolin and 46% when untreated; unwounded reached only about 3% diseased fruits.
Nevertheless, symptoms caused on wounded fruits are less severe than natural ones and this aspect deserves further investigations especially centered on disease cycle.
This injury must be recorded as potentially very dangerous, mainly due to its widespreading but also because the possibility that the pathogen will develop more virulent physiological races.