Explanation :

• Yellow rust or stripe rust (Puccinia striiformistritici) is an important disease of wheat (Triticum aestivum), especially in cool climates.
• Ripe rust of wheat is caused by the basidiomycete fungus Puccinia striiformis in the order Uredinales.
• It is considered to be an obligate parasite.
• The symptoms are symmetrical “stripe” lesions along the leaf, bearing orange-yellow pustules. These are located just underneath the upper leaf layer (epidermis), and are much less compact than brown rust pustules.
• The ideal growth conditions for yellow rust are temperatures of between 8-13°C for spore germination and penetration, and 12-15° C for further development and with free water.