Philodendron brandtianum (Silver Leaf Philodendron)

Leaf spot is a common fungal disease caused by various pathogens including Alternaria, Ascochyta, Colletotrichum, Septoria, and Venturia. It primarily affects leaves, causing discolored spots that can lead to premature leaf drop if left untreated.

Powdery mildew is a common fungal disease caused by various fungi species including Erysiphe, Podosphaera, Oïdium, and Leveillula. It affects over 10,000 plant species worldwide. The disease thrives in warm, dry climates with high humidity and appears as a distinctive white powdery coating on plant surfaces.

The Phytophthora genus consists of soil-borne oomycetes (water molds) that act as plant pathogens, primarily affecting trees and woody plants. It typically spreads through the root system, leading to systemic decline and eventual plant collapse.

Southern blight is a devastating soilborne fungal disease caused by Athelia rolfsii (formerly Sclerotium rolfsii), affecting over 500 plant species including vegetables, ornamentals, and fruit crops. The fungus survives in soil through resting structures called sclerotia that resemble mustard seeds and can remain viable for years.

Erwinia is a genus of plant-pathogenic bacteria that cause fast-spreading rots and blights. On apple and pear, Erwinia amylovora causes fire blight: tender shoots wilt, turn dark, and often bend like a shepherd’s crook; blossoms and twigs may ooze a sticky, amber liquid. In vegetables and many houseplants, related Erwinia-type bacteria cause soft rot: leaves or stems look water-soaked, turn mushy, and smell bad, often starting at wounds or at the crown. These bacteria spread by splashing water, insects, dirty tools, and infected plant parts, especially in warm, wet weather.

Pseudomonas is a group of bacteria that causes leaf spots, blights, cankers, and soft rots on many garden and houseplants. It thrives in cool, wet, or humid weather and spreads with splashing water, rain, handling, and contaminated tools. Look for small, water‑soaked spots that turn dark brown or black, often with a yellow halo; on tomatoes, these can appear as tiny dark specks on leaves and fruit. On woody plants such as cherry, plum, and lilac, it can cause sunken cankers, oozing, dieback, or blossoms that fail after a cool, wet spring. Succulents and fleshy tissues may develop soft, slimy rot. Commonly affected plants include tomatoes, peppers, beans, brassicas, roses, lilacs, stone fruits, and various houseplants.

Xanthomonas is a group of bacteria that causes leaf spots and blights on many garden and indoor plants. It spreads through splashing water, wet tools, hands, and infected seed or cuttings. Early signs are small, water‑soaked spots that turn yellow, brown, or black; spots often have a yellow halo and can look angular because veins limit their shape. Leaves may yellow, tear, or drop; stems and fruit can develop dark, sunken lesions. Commonly affected plants include tomato and pepper, brassicas (such as cabbage), beans, citrus, orchid, philodendron, coleus, and many other ornamentals.