Nectriella

Nectriella is a genus of ascomycete fungi that can act as pathogens on various plant species. This disease is typically characterized by necrotic lesions and ulcers that develop on the bark, branches, or stems of host plants. If left untreated, the infection causes significant structural damage to the plant, leading to stunted growth or total decline.

The causal agents are fungi belonging to the order Hypocreales. The disease type is defined as a necrosis-type pathology, where the fungus penetrates the plant tissue, colonizes the bark and cambium, and disrupts the vascular system. This disruption prevents the movement of water and nutrients, resulting in the localized death of plant tissues.

Host plants primarily include woody perennials, such as orchard trees, berry bushes, and certain ornamental species. The fungus frequently attacks specimens that have already been weakened by environmental stressors, such as harsh winters, drought, or mechanical damage caused by pruning or insect activity.

Common symptoms include the appearance of discolored, sunken areas on the bark. As the fungus matures, it produces fruiting bodies known as perithecia, which appear as tiny, brightly colored or dark clusters on the surface of the lesion. Infected branches may show wilting, leaf chlorosis, and, in advanced stages, dieback of the crown.

The development of Nectriella is highly dependent on humidity levels and moderate temperatures, which favor spore production and germination. The pathogen spreads primarily through windborne spores and splashing rain, as well as through contaminated pruning tools. Prevention is key to controlling the spread, especially in high-density plantings.

• Prune and destroy all infected plant material immediately.
• Sanitize pruning tools with alcohol or a bleach solution between cuts.
• Maintain tree health through proper fertilization and irrigation.
• Apply copper-based fungicides as a preventative measure during dormant periods.
• Improve air circulation within the canopy to reduce localized humidity.