Final answer:
Nutrient deficiency is the most common cannabis ailment causing chlorosis of older leaves and potentially red stem discoloration. It also can result in stunted leaf growth and cell necrosis in extreme cases. Plants have mechanisms like nutrient recycling to manage declining tissue.
Step-by-step explanation:
The most common cannabis ailment, especially noticeable in the first week of flowering and again towards the end, is typically caused by a nutrient deficiency. This condition is characterized by a chlorosis of the older leaves, starting at the edges and working inwards. As the condition progresses, new leaves may not reach their full size, and you might even observe a red discoloration of the stem. Nutrient deficiencies can lead to various plant health issues, including stunted growth, slower than normal growth rates, and chlorosis, which is a term used to describe the yellowing of the leaves. Extreme deficiencies might cause cell necrosis, where plant cells die, which can become evident in the leaves. Plants continue to grow in spite of dead tissue and implement a process called nutrient recycling, where components from declining parts are repurposed for developing seeds or storage.