natural-products-in-plant-pest-management

34 S. Marín et al.50 mg/ml lecithin. All treatments were tested at 18 and 50°C. Fruits weredipped in the treatment solutions. After 2 min of treatment, fruits werestored at 2°C at normal atmosphere. Significant disease incidence reductionswere observed in fruits treated with eugenol mixed with lecithin at50°C; this combination reduced the incidence of P. expansum by 60–90%. Thelecithin–eugenol formulation did not induce immediate or delayed phytotoxicityat room temperature. Investigation of its vapour phase propertiesand its applicability in the storage room will surely facilitate the applicationof eugenol as a control agent for long periods and may avoid the problemsof phytotoxicity induced by some liquid formulations (Amiri et al.,2008).Essential oils of Caesulia axillaris and Mentha arvensis were applied at1500 and 1000 μl/l to the storage atmosphere of P. italicum inoculated oranges.The Caesulia-oil-treated oranges showed an increased storage life of 3 days,and the Mentha oil-treated oranges showed an increase of 7 days. No visualsymptoms of possible injury caused by the oils were observed on the peel ofthe fruits (Varma and Dubey, 2001).Aspergillus section Nigri (formerly A. niger) is an ubiquitous fungalcontaminant of foodstuffs, such as fruits, vegetables, nuts and spices. Somespecies in this section have been recently shown to produce ochratoxin A.Pepperfruit (Dennetia tripetala) extracts have been tested in tomato pureeagainst common spoilage fungi, including A. niger. Extracts, as a single hurdle,failed to inhibit fungal growth when compared to counts before treatment.Moreover, the use of extracts alone would entail the use of concentrationsthat may affect the sensorial properties of the tomato; however, combiningwith heat treatment (80°C for 1 min) or NaCl addition (10 mg/g) resulted ineffective treatments (Ejechi et al., 1999). Cinnamon essential oil has beentested against a range of fungi isolated from tomato, including A. niger.Although in vitro experiments showed promising results in terms of colonydevelopment and fungal sporulation inhibition, when cinnamon oil wastested as a volatile in the atmosphere of stored tomatoes and peppers nomajor effects were observed (Tzortzakis, 2009). Tomatoes and strawberriesexposed to an enriched oil vapour showed improved fruit-quality-relatedattributes, confirming the benefits observed after exposure to cinnamon oilvapour at different concentrations. These findings may have considerablecommercial significance.Extracts of Zingiber officinale and Xylopia aetiopica were added (1–3%) toA. niger, A. flavus or Rhizopus stolonifer inoculated orange and apple juices.Although growth was reduced, the extracts either alone or in combinationdid not impose enough stress to stop the growth of the fungi (Akpomeyadeand Ejechi, 1999).The advantage of essential oils is their bioactivity in the vapour phase andthe limitation of aqueous sanitation for several commodities (e.g. strawberriesand grapes) make the essential oils useful as possible fumigants for storedcommodity protection. One limitation of the essential oils is the strongflavour they impart, thus restricting their applicability only to products witha compatible flavour.