Stemphylium infection causes small, round to irregular water‑soaked spots on leaves that turn brown‑gray with darker margins and sometimes concentric rings or yellow halos. Lesions can coalesce, causing blight, leaf dieback and defoliation; stems and fruit may develop sunken spots or rot. Dark fungal fruiting bodies may be visible in lesions in humid conditions, and severe infections reduce yield.

Rhizoctonia solani is a soil‑borne fungus that causes damping‑off of seedlings, root rot and stem canker in many crops. It also produces sheath blight in rice and brown patch in turfgrass. Infected plants develop brown, sunken lesions on roots or stems, poor seedling emergence, wilting and reduced vigor, often leading to plant death under favorable conditions.

Stemphylium is a fungal plant pathogen found worldwide on leaves of many crops (onion, garlic, pear, tomato, legumes, soybeans) and wild plants. It survives in infected plant debris and soil, and its spores disperse by wind, rain splash, contaminated seed and tools. Infections are favored by warm, humid conditions and can persist between seasons in crop residues.

Alternaria solani causes early blight, a fungal disease primarily of tomato and potato plants. It produces concentric dark leaf spots, yellowing and premature leaf drop, stem lesions and fruit rots, reducing yield. Disease thrives in warm, humid conditions and spreads via spores on debris. Management includes crop rotation, removing infected debris, resistant varieties, proper spacing, mulching, and timely fungicide use.

Stemphylium allergy is an IgE-mediated hypersensitivity to airborne spores of Stemphylium fungi. It commonly causes allergic rhinitis, conjunctivitis, cough, wheeze or asthma exacerbations and occasional skin rashes after agricultural or mold exposure. Diagnosis uses clinical history, skin-prick or specific IgE testing. Management focuses on avoidance and symptomatic treatment (antihistamines, intranasal steroids, inhaled bronchodilators/corticosteroids) and specialist assessment for immunotherapy.

Mould exposure can cause respiratory symptoms—nasal congestion, sneezing, coughing, wheeze and throat or eye irritation—plus sinusitis and shortness of breath. Other effects include persistent cough, chest tightness, skin rashes or itching, headaches, fatigue, muscle aches and trouble concentrating or memory problems. Severe or invasive mould infections can cause fever and systemic illness, especially in people with weakened immune systems.