Distribution of Peach latent mosaic viroid in Commercial Orchards of Peach in the North of Tunisia

Abstract

The presence of Peach latent mosaic viroid (PLMVd) was monitored during 2 years in peach orchards located in the North of Tunisia. PLMVd population was surveyed using a specific RT-PCR test adapted to crude sap extract. During the first year (2004), 228 samples were randomly selected in 22 peach orchards (eight cultivars) and tested for the presence of PLMVd. Results showed that PLMVd is highly and equally present in four regions of the North of Tunisia. Analyses of some key factors in relation to PLMVd incidence revealed that the tree age did not influence the infection rate. The eight studied cultivars were clustered in three groups according to their PLMVd incidence. Furthermore, the early and season cultivars were statistically more infected than the late cultivars. Prospections in May and October 2005 were performed in four selected orchards. Each two orchards contained Early May Crest (early cultivar) and Carnival (late cultivar) cultivars, respectively. The difference in PLMVd incidence observed in 2004 was confirmed. Furthermore, no correlation between the tree physiological state and the viroid detection was observed. Further investigations on the origin of the differences in PLMVd incidence between Early May Crest and Carnival cultivars would be of interest.

Occurrence of target‐site resistance to neonicotinoids in the aphid Myzus persicae in Tunisia, and its status on different host plants

“…In Tunisia, M. persicae attacks arable crops including potato, sugar beet and tobacco, horticultural crops in the families Brassicaceae, Solanaceae and Cucurbitaceae, and top fruit (especially peach, apricot and citrus). The greatest damage occurs in peach orchards and open field plantings of potato and tomato . The history of insecticide use against M. persicae in Tunisia mirrors that in many other countries with the efficacy of organophosphates, carbamates and pyrethroids having been progressively eroded by resistance .…”

“…The greatest damage occurs in peach orchards and open field plantings of potato and tomato. 4,18 The history of insecticide use against M. persicae in Tunisia mirrors that in many other countries with the efficacy of organophosphates, carbamates and pyrethroids having been progressively eroded by resistance. 19 In the last decade, control of M. persicae has become increasingly reliant on neonicotinoid insecticides, although the continuing effectiveness of this class has also been questioned.…”

Low incidence of peach latent mosaic viroid in peach mother blocks in Serbia

“…Peach latent mosaic disease occurs worldwide. The incidence of PLMVd in germplasm of different geographical origins is generally high and ranges from 40-90% (Fekih Hassen et al, 2007). Numerous studies have shown that PLMVd is transmitted by grafting, budding, contaminated blades or pollen, but not by seed (Hadidi et al, 1997;Desvignes et al, 1999;Barba et al, 2007;Faggioli & Barba, 2008).…”