Tomato: Edible Plant

Verticillium wilt is a soil-borne fungal disease caused primarily by the fungi Verticillium dahliae and V. albo-atrum. These pathogens infect plant roots and grow within the vascular tissues, blocking water and nutrient transport, resulting in wilting and eventual plant death. The disease affects over 350 plant species including vegetables, fruits, ornamental flowers, and trees. The fungi can survive in soil for more than 10 years as resistant structures called microsclerotia.

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.

Damping off is a soil-borne fungal disease that affects seeds and young seedlings, causing rotting of stem and root tissues at and below the soil line. It is caused by several fungi including Pythium, Rhizoctonia, Fusarium, and Phytophthora. The disease thrives in cold, wet conditions with poor air circulation.

Anthracnose is a fungal disease caused by fungi in the genus Colletotrichum that affects many plants, including vegetables, fruits, and trees. The disease thrives in cool, wet conditions, causing dark, sunken lesions on leaves, stems, flowers, and fruits.

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.

Gray mold, caused by the fungus Botrytis cinerea, is a widespread necrotrophic pathogen affecting over 1,400 plant species. It thrives in cool, humid conditions and attacks weakened or aging plant tissues, causing soft rot and characteristic gray fuzzy growth.

Disease caused by fungus-like organisms (oomycetes) that live in soil and can survive for years. It affects roots, stem, and crown of plants, being especially severe in waterlogged or poorly drained soils. It is the second most common cause of root rot in trees and shrubs.

Bacterial wilt is a fatal vascular disease caused by bacteria (Erwinia tracheiphila, Ralstonia solanacearum, Xanthomonas spp.) that infects the water-conducting tissue of plants. The bacteria multiply and block the flow of water and nutrients, causing rapid wilting and plant death within 1-2 weeks.

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.

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.

Tomato Spotted Wilt Virus (TSWV) is one of the most devastating viral diseases affecting over 1,000 plant species across 85 families. It is transmitted by thrips and cannot be cured once a plant is infected. The virus causes severe stunting, bronzing of leaves, necrotic spots, and significant yield losses. Early detection and removal of infected plants is critical to prevent spread.

Leaf curl virus is a serious viral disease caused by begomoviruses, transmitted by whiteflies (Bemisia tabaci). It affects various plants including tomatoes, peppers, and ornamentals, causing significant yield losses and plant decline. Once infected, plants cannot be cured and management focuses on prevention and vector control.

Aphids are small, soft-bodied, pear-shaped insects (1/16 to 1/8 inch long) that feed by sucking nutrient-rich sap from plants. They reproduce rapidly and can quickly weaken plants, causing distorted growth and transmitting plant viruses. Aphids come in various colors including green, black, red, yellow, brown, and gray. They secrete honeydew, a sticky substance that attracts ants and encourages sooty mold growth.

Whiteflies are small, soft-bodied, winged insects closely related to aphids and mealybugs. They are moth-like in appearance, about 1/16 inch long, triangular in shape, and gray-white in color. These sap-sucking pests feed on plant tissue, causing yellowing, stunted growth, and wilting. They also excrete honeydew, which attracts ants and promotes sooty mold growth. Whiteflies can transmit serious plant viruses.

Thrips are tiny cigar-shaped insects (1/25-inch long) that damage plants by sucking plant juices and scraping at fruits, flowers, and leaves. With over 6,000 species and rapid reproduction (lifecycle as short as 14 days), they can quickly infest plants and transmit viruses like tomato spotted wilt virus.

Root-knot nematodes (Meloidogyne species) are microscopic roundworms that parasitize plant roots, causing characteristic galls or knots. These soil-borne pests are among the most economically damaging plant pathogens worldwide, affecting a wide range of ornamental and edible plants. The nematodes inject enzymes into root cells, causing abnormal swelling and disrupting water and nutrient uptake.

Calcium deficiency is a common plant disorder caused by insufficient bioavailable calcium in the growing medium or, more frequently, by low transpiration rates that prevent proper calcium transport to new growth. It manifests as necrotic leaf margins, curling of young leaves, stunted growth, and in severe cases, conditions like blossom end rot in fruits. The disorder primarily affects rapidly growing tissues where calcium demand is highest.

Nitrogen deficiency occurs when plants lack sufficient nitrogen, an essential macronutrient needed for chlorophyll production and overall growth. This deficiency typically manifests as yellowing leaves, starting with older foliage and progressing to newer growth if left untreated.

Potassium deficiency is a nutritional disorder that affects a plant's ability to regulate stomatal opening and closing, resulting in characteristic leaf edge burn. Potassium is a mobile nutrient, so symptoms first appear on older, lower leaves.

Phosphorus deficiency is a common nutritional problem that hinders healthy plant growth. Phosphorus is essential for root development, flowering, fruiting, and energy metabolism. When deficient, plants exhibit stunted growth and leaves with purple or reddish coloration, especially on older leaves.

Magnesium deficiency is a nutrient disorder characterized by interveinal chlorosis, where leaf tissue between veins turns yellow while the veins remain green. This deficiency affects older leaves first as magnesium is a mobile nutrient that plants relocate to support new growth. Magnesium is essential for chlorophyll production and photosynthesis, making this deficiency critical for plant health.

Overwatering occurs when plants receive too much water, depriving roots of oxygen and causing root rot. This environmental stress is one of the most common causes of houseplant death, as waterlogged soil prevents roots from breathing and functioning properly.

Sunburn or sun scorch is an environmental condition that occurs when plants are exposed to intense, direct sunlight beyond their tolerance level. This causes the breakdown of chlorophyll in the leaves, resulting in bleached, dried, and damaged foliage. The damage can happen rapidly, sometimes within just a few hours of exposure.