Mustard (genus Sinapis)

Downy mildew is a fungal-like disease caused by oomycetes (water molds) that thrives in cool, wet conditions. It affects a wide range of plants, causing yellowing leaves with fuzzy white-gray growth underneath, leading to defoliation and reduced yields if left untreated.

Alternaria leaf spot is a common fungal disease caused by Alternaria solani and Alternaria alternata that affects a wide range of plants including tomatoes, potatoes, brassicas, and ornamentals. The disease thrives in warm, humid conditions and can cause significant crop damage if left untreated. Spores overwinter on plant debris and can attach to seeds, making complete elimination difficult.

White mold (Sclerotinia sclerotiorum) is a devastating fungal disease affecting over 400 plant species worldwide. The fungus produces black, seed-like structures (sclerotia) that can survive in soil for 5 or more years. The disease is favored by cool, moist weather (50-68°F/10-20°C), especially during flowering.

Bacterial leaf spot is a plant disease caused by bacteria in the Xanthomonas and Pseudomonas genera that affects various ornamental and edible plants. The bacteria infect leaves through wounds or natural openings, causing characteristic lesions that can lead to premature leaf drop and plant weakening.

Cercosporella is a group of leaf-spot fungi that cause spotting and blight on many plants, especially in cool, damp, or crowded conditions. Early symptoms are small tan to gray spots with darker borders on leaves. Spots can merge into larger patches; leaves may yellow, dry out, and drop. In wet weather, a fine, dusty or velvety layer can appear on the underside of leaves. It spreads by splashing water, wind, tools, and infected plant debris. Common hosts include lettuce and other salad greens, beets and chard, brassicas (such as cabbage and kale), ornamentals (including delphinium and chrysanthemum), and small grains like wheat and barley.

Mosaic virus is a group of plant viruses that cause mottled, patchy patterns on leaves and can affect a wide variety of plants. The virus creates characteristic yellow, white, and green mosaic patterns, often accompanied by stunted growth and deformed plant parts. This highly contagious disease spreads rapidly through insect vectors and contaminated tools.