African Spear: Low Water Needs

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.

Fusarium wilt is a serious fungal disease caused by the soil-borne fungus Fusarium oxysporum. The fungus invades roots and blocks the water-conducting vessels (xylem) of the plant, causing progressive wilting and eventual death. Host-specific forms of the pathogen exist that attack different plant species.

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.

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.

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.

Gray mold, caused by the fungus Botrytis cinerea, is one of the most common fungal diseases in plants. It affects over 200 plant species, including ornamentals, vegetables, fruits, and houseplants. The disease thrives in cool, humid conditions with poor air circulation, causing grayish spots and soft rot on infected tissues.

Bacterial soft rot is a destructive plant disease caused primarily by bacteria from the genera Pectobacterium (formerly Erwinia) and Dickeya. These bacteria produce enzymes that break down plant cell walls, causing rapid and foul-smelling tissue decomposition. It mainly affects succulent tissues such as tubers, fruits, stems, and bulbs, being especially problematic in warm and humid conditions.

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.

Bacterial blight is a serious plant disease caused by pathogenic bacteria that enters plants through wounds or natural openings. It spreads rapidly in warm, wet conditions and can cause significant damage to leaves, stems, and flowers. The bacteria are transmitted by water splash, contaminated tools, and insects.

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.

Mealybugs are small, soft-bodied insects covered with a white, waxy, cottony material. They are common pests of houseplants and outdoor plants in mild climates. These sap-sucking insects feed on plant tissue, causing damage, stunted growth, and can lead to plant death if left untreated. They produce sticky honeydew which attracts sooty mold.

Spider mites are tiny arachnids (less than 1/20 inch long) related to spiders and ticks that feed on plant sap. They thrive in hot, dry conditions and can cause significant damage to ornamental and vegetable plants. During severe infestations, crop losses can reach 14% or higher as these pests disrupt vital plant processes including photosynthesis, carbon dioxide absorption, and transpiration.

Scale insects are small sap-sucking pests that appear as brown, shell-like bumps on plant stems and leaves. There are over 25 species, divided into armored (hard) and unarmored (soft) scales. They feed by piercing plant tissue and extracting sap, which weakens the plant and can lead to yellowing, stunted growth, and even death if left untreated. They also excrete honeydew, which attracts ants and promotes sooty mold growth.

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.

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.

Fungus gnats are small, gray-to-black mosquito-like insects (1/8 to 1/10 inches long) commonly found in indoor plants. Adult gnats are mostly a nuisance, but their larvae feed on plant roots and organic matter in soil, potentially causing serious damage to young or vulnerable plants. The larvae are translucent white with distinctive black heads and can leave slime trails on the soil surface in heavy infestations.

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.

Iron deficiency, commonly known as iron chlorosis, is a nutrient deficiency disorder where plants cannot access sufficient iron from the soil. While iron is typically abundant in soil, various soil conditions can limit plant uptake, resulting in characteristic yellowing of leaves while veins remain green.

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.

Underwatering or drought stress is a physiological disorder that occurs when the amount of water a plant loses through transpiration exceeds the amount its roots can absorb from the soil. This leads to cellular dehydration and various visible symptoms that can compromise plant health and productivity.

Cold damage, also known as frost injury, occurs when plants are exposed to freezing or near-freezing temperatures. This environmental stress can cause cellular damage as ice crystals form within plant tissues, rupturing cells and disrupting normal plant functions. Chilling injury can also occur in sensitive species at temperatures between 32-55°F (0-10°C), even without actual freezing.

Heat stress occurs when plants are exposed to excessively high temperatures, typically above 85-90°F (29-32°C), causing physiological damage and compromising vital processes such as photosynthesis and transpiration.

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.

Low light stress, also known as etiolation, occurs when plants do not receive adequate light for proper growth and development. This leads to abnormal growth patterns characterized by elongated stems, pale leaves, and weakened overall structure as the plant attempts to reach toward available light sources.

Low humidity stress occurs when indoor air becomes too dry, causing plants to lose moisture faster than they can absorb it through their roots. This is especially common during winter heating periods, near radiators and heating vents, or in air-conditioned spaces. Tropical plants are particularly susceptible to low humidity damage.

Root-bound, also called pot-bound, is a common environmental condition that occurs when a plant's roots have outgrown their container. The roots become so densely packed that they circle around the root ball and cannot expand properly. This restricts the plant's ability to absorb water and nutrients, leading to stunted growth and declining health. Unlike diseases, being root-bound is not contagious and is entirely preventable through proper container management and regular repotting.

Salt buildup (also called salt accumulation or fertilizer salt deposits) is an environmental condition where mineral salts accumulate in the soil over time, creating a toxic environment for plant roots. The most visible sign is a white or yellowish crusty layer on the soil surface or around pot edges.

Fertilizer burn is a condition caused by applying excessive fertilizer to plants. The salts in fertilizer draw moisture out of plant tissues, leading to scorched foliage, root damage, and overall plant stress. This environmental condition is not contagious and can be reversed with proper treatment.

Transplant shock is a stress response that occurs when plants are abruptly moved from one environment to another. This environmental condition affects plants during repotting, moving between indoor/outdoor locations, or transplanting from nursery pots to gardens. Root damage during the move is the primary cause, making it nearly impossible to completely avoid some degree of stress.

Leaf tip necrosis, also known as tip burn, is a non-infectious environmental condition where the tips and edges of leaves turn brown, dry, and crispy. This occurs due to various stress factors affecting the plant's ability to maintain healthy tissue at the leaf extremities.

Edema (also spelled oedema) is a non-infectious physiological disorder caused by an imbalance between water uptake and transpiration. When roots absorb water faster than leaves can release it through transpiration, cells in the leaf tissue swell and burst, forming characteristic wart-like blisters. This is purely a cosmetic issue and does not threaten plant health.

Chemical burn (phytotoxicity) occurs when plants are damaged by misapplication or misuse of pesticides, herbicides, fertilizers, or other chemicals. Environmental conditions like high temperatures, humidity, and plant stress increase vulnerability. Unlike diseases, chemical damage is not contagious but can severely harm or kill plants if not addressed promptly.