![]() ![]() (1994) reported losses of 46% in their fungicide efficacy study in the same location. ![]() (1995) reported yield losses ranging from 11 to 25% in Poza Rica, Veracruz, Mexico, although the details of this study were not revealed either. Hock (1988) mentioned losses of 30% of maize yields but did not specify the details of the study. Most of the information regarding yield losses caused by TSC is anecdotal. The disease complex has been reported in several Latin American countries and was considered to be confined to the tropical areas of the region ( Hock et al., 1989). It was suggested that optimal temperature for the development of the disease is 16–18☌ (± 5–7☌) with a monthly average rainfall of 150 mm and 10–20 foggy days per month ( Hock et al., 1989). (1989) proposed the potential involvement of phytotoxin production in TSC, as a cause of the rapid foliage “burning” effect. In the case of severe TSC epidemics, the chlorotic halos coalesce and the entire plant can become necrotic approximately within a week. maydis, its role in TSC is still not clear, and it is believed to be a hyperparasite or mycoparasite, with no obvious host symptom expression ( Ceballos and Deutsch, 1992 Hock et al., 1992). phyllachorae is often isolated from the leaves infected by P. maydis can be present as pathogens in a plant independently, or if infection in maize is triggered only by their simultaneous co-occurrence. maydis ( Dittrich et al., 1991 Hock et al., 1992). maydis is thought to be an endophyte or facultative parasite, causing extensive chlorosis in the presence of P. Approximately within 1 month, the disease symptoms progress from lower to upper leaves. ![]() Approximately 2 weeks later, the area surrounding the stromata becomes chlorotic, forming a halo-like effect that is often referred to as the typical “fish-eye” symptom of TSC, which is caused by M. maydis erupting through the epidermis of the lower and central leaves ( Figure 1A). The initial symptoms of the disease appear as dark oval or irregularly shaped stromata of P. is also often associated with TSC ( Hock et al., 1989). A third fungus, Coniothyrium phyllachorae Maubl. and Monographella maydis Müller & Samuels. The disease is caused by the interaction of two fungal pathogens, Phyllachora maydis Maubl. Tar spot complex (TSC) is a major foliar disease of maize in many regions of Latin America. Challenges and opportunities in the use of RS technologies for disease resistance phenotyping are discussed. This may help reduce the cost and time required for the development of improved maize germplasm. Our results suggest that the RS techniques tested in this study could be used for high throughput phenotyping of TSC resistance and potentially for other foliar diseases of maize. In addition, we demonstrated that TSC could cause up to 58% yield loss in the most susceptible maize hybrids. A strong relationship was also observed between the area under the disease progress curve of TSC and three vegetative indices (RDVI, MCARI1, and MCARI2). A strong relationship between grain yield, a vegetative index (MCARI2), and canopy temperature was observed under disease pressure. In this study, several multispectral vegetation indices (VIs) and thermal imaging of maize plots under disease pressure and disease-free conditions were tested using an unmanned aerial vehicle (UAV) over two crop seasons. Although remote sensing (RS) techniques are increasingly being used for plant phenotyping, they have not been applied to phenotyping TSC resistance in maize. maydis was also detected in the United States of America in 2015 and since then the pathogen has spread in the maize growing regions of the country. Tar spot complex (TSC), caused by at least two fungal pathogens, Phyllachora maydis and Monographella maydis, is one of the major foliar diseases of maize in Central and South America.
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