Assessment of production and dispersal of inoculum ofAlternaria Macrospora in various parts of the cotton canopy
Morning and evening counts of spores ofAlternaria macrospora in a cotton (Gossypium barbadense) field were assessed for the number of spores (a) produced on the last night, (b) dispersed during the day, and (c) retained in the spore reserve on leaves. Throughout the season, 1 m2 of the field produced (P) and dispersed (D) approximately 163 x 106 and 137 x 106 spores, respectively. The 16% discrepancy between P and D values reflects experimental errors. Most spores were produced on shed leaves on the ground, fewer on leaves in the lower part of the canopy, and least on leaves in the upper canopy. The contribution to total D decreased from leaves in the lower part of the canopy, to shed leaves, and to leaves in the upper canopy. In tests with potted plants with spore-bearing lesions attached to various heights of the canopy under various conditions of weather, dispersal of spores at these heights was conditioned mainly by wind velocity, which decreased from the upper to the lower part of the canopy. In leaves close to the ground, approximately 29% of the released spores were removed by sedimentation to the ground. On any one day, the daily rate of D differed from the daily rate of P. On days in which D was higher than P, the difference was due to a reserve of spores remaining on lesions after dispersal during the previous days. In weather adverse for production of new spores, the reserve was depleted within 4 and 6 days in the top and bottom leaves, respectively, but remained relatively high in the shed leaves on the ground; a similar number of days was needed to restore the depleted reserve in sporulation-favorable weather.
The infection process, sporulation and survival of Alternaria helianthi on sunflower
SUMMARY 
 
Electron microscopy was used to study the infection of sunflower leaves by Alternaria helianthi. Conidia germinated by producing one to many germ tubes which grew across the leaf surface before forming appressoria. The fungus directly penetrated its host through the cuticle and epidermis. Entry into the host through wounds and stomates was also observed. Extracellular sheaths were found to be associated with germ tubes and intercellular hyphae of A. helianthi. Conidiophores developed through collapsed stomates, from leaf veins, trichomes and also from mycelium growing across the host leaf surface. Microcylic conidia were produced directly from parent conidia under certain conditions. Studies using a volumetric spore trap showed that the airborne spore concentration followed a distinct periodicity with peaks occurring between 0900 and 1100 h each day. Laboratory studies showed that safflower, noogoora burr and bathurst burr could serve as alternative hosts for A. helianthi. The pathogen was readily isolated from sunflower crop debris from a diseased crop that had been harvested 1 yr earlier.
Do Arab public opinion support policies of regional powers in MENA? View from Tunisia
ABSTRACT The Arab Uprisings and subsequent events continue to transform policies of regional and major powers toward the Middle East and North Africa. These powers have shown different approaches toward the Uprisings, ranging from support for the status quo to endorsing regime changes. Their policies have also exerted a significant impact on the course of events. Despite this growing importance and implications of policies of regional powers on the Uprisings and the Syrian conflict, we still do not know much about how the public assesses these policies and to what extent domestic cleavages shape these assessments. Using a nationally representative original survey conducted in 2014 in Tunisia, this study examines the perceptions of the policies of France, Turkey, and Saudi Arabia towards the Uprisings and the Syrian conflict. It finds that French and Turkish policies about the Uprisings have garnered substantial support among citizens, whereas most citizens negatively assess the Saudi policies. On the other hand, the majority of Tunisians negatively assess all these countries’ policies toward the Syrian conflict. Another major finding suggests that political identity reflecting secular/religious cleavages shapes how citizens view the policies of these three countries toward both issues, but its effect is higher in assessing the Uprisings.