Which of the following is NOT considered an environmental condition of apple scab?

In the context of apple scab, environmental conditions play a crucial role in the development of this fungal disease, caused by the pathogen Venturia inaequalis. The correct answer pertains to 'Dry' conditions, as they are generally not conducive to the infection and spread of apple scab.

Apple scab thrives in moist environments, where humidity and consistent wetness are key to the germination of the fungal spores and infection of the apple trees. High rainfall, along with cool spring weather, creates ideal conditions for the disease, allowing it to proliferate and cause significant damage to the foliage and fruit.

In contrast, dry weather does not support spore germination and reduces the potential for disease development. Thus, labeling dry conditions as not considered an environmental factor for apple scab aligns with the understanding that moisture is necessary for this particular disease to flourish.