Pests- Rabbits and deer eat our elderberry plants. We keep our plants surrounded by an electric fence. Deterrents may be necessary for your plants such as fencing or spreading Milorganite. Birds will eat the elderberry fruit. Some growers use netting over the cymes to help prevent loss of fruit. Cultivars such as Bob Gordon Elderberry grow the cymes ‘upside down’ which helps deter the birds.

The following information on Insect management has been sourced from the West Virginia University horticulture extension. 

https://extension.wvu.edu/agriculture/horticulture/elderberry

Insect Management

Elderberries have relatively few pest and health problems. Though, a few new invasive species are presenting a serious threat – spotted wing drosophila being one of the newest problems. Some other common elderberry pests are Japanese beetle, elderberry shoot or cane borer, elder borer beetle and eriophyid mites.

Spotted Wing Drosophila

Spotted wing drosophila is a new invasive species that came to the United States from Asia. It was first discovered in California in 2008 and has since been reported in most states. It has been in West Virginia since 2011. SWD is particularly attracted to the ripening fruit. Eggs are deposited in fruit as it ripens and in over-ripe fruit. Larvae feed within the fruit, causing it to become soft and drop. Monitoring is essential to determine the emergence and presence of the insect to plan effective control. 

Eriophyd Mites

These mites are very small and cannot be seen by the naked eye. They overwinter under the bud scales with their highest number near the terminal growth. The symptoms of their presence appear as crinkling, folding and cupping of the leaves. They do not life-threatening damage. Most often, beneficial mites take care of them so the miticide applications are not necessary.

Japanese Beetle

Japanese beetles ( Popillia japonica) are foliar feeders and can inflict serious damage to the leaves. The beetle overwinters in its larval form, referred to as grubs. Larvae burrow themselves 8 to 10 inches deep in the soil to avoid being killed by the frost. Grubs start ascending toward the surface as the soil warms up. Along the way, they will feed on the roots of mainly grasses, but they are not partial to them and will consume anything edible in their way. By late May to early June, they will pupate and emerge as adults at the end of June to mid-July. The adult beetles will spend the next 30 to 45 days feeding and mating. Females will lay the eggs 2 to 6 inches deep in the soil during July and August. It takes 10 to 12 days for the eggs to hatch. The new grubs inflict damage as they feed on organic matter in the soil, mainly roots. As the temperature drops and the soil cools, they move deeper into the soil where they wait until next spring to start the cycle all over again. Grubs spend up to 10 months underground. Normally, there is only one generation a year, but in the northern areas, the species may take two years to complete the life cycle.

Cane or Shoot Borer

Cane or shoot borers ( Achatodes zeae) are moths. The eggs hatch in April to May and larvae first start feeding on young, developing leaves. Soon after, larvae start boring into the young shoots, leaving a visible hole on it. They start burrowing into lateral shoots then migrate toward the lower part of the main, primary stem, near the ground. They feed on the inner side of the cane causing wilting and die-back. In early summer, fully grown larvae will move from shoots into the dead canes and pupate. Adult moths emerge from the dead canes and will start laying eggs in July and August in canes that are at least one year old. Eggs hatch the following spring. Sanitation or removal of the dead and/or infested canes is part of shoot borer management. 

Elderberry Borer Beetle

The female elderberry borer beetles ( Desmocerus palliates) lay their eggs near the plant base. Hatched larvae burrow their way into stem, tunneling and eating their way into roots. As they mature, larvae migrate from roots upward into canes, where they pupate. It may take up to two years for the larvae to mature. The adult beetles emerge and feed on leaves and flowers. 

Disease Management

There are a few diseases found in elderberries. Some present a perennial problem, while others may be more sporadic, driven by the environmental conditions each year. For infection to occur and disease to develop, three things must coincide – presence of a susceptible host, presence of a pathogen, and suitable environmental conditions (rain/moisture, duration of wetting period, temperature, wind, etc.). 

Pathogens causing elderberry diseases are fungi and viruses. Disease control success will greatly depend on recognizing symptoms and knowing biology and requirements needed for disease development. Manipulation of these micro-environmental factors through cultivation, sanitation, weed suppression and other cultural practices will aid in combating the problem. 

Tomato Ringspot Virus

Tomato ringspot virus (TmRSV) is probably the most important and most serious disease that attacks elderberry plants. It will weaken the plant, leading to reduced production, and can even kill the plant. It is spread by nematodes, certain weeds like dandelions, and pollen. The foliar symptoms on leaves usually show chronic line patterns, oak-leaf pattern and sometimes green spots, while some plants can show just a general chlorosis or a light-green, dark-green mottle. Unfortunately, there is no cure for this virus and what started as plant decline, reduction in yield, shoot dieback and cold temperature survivability will lead to the death of a plant. It is a good practice that a virus-infected plant be removed from the planting and destroyed by burning. Whenever pruning plants that might be virus infected, it is necessary to observe strict tool sanitation after each cut. Prevention is the best management practice. Even before planting, soil should be checked for nematodes that carry and transmit the viruses. Weed control is part of a good TmRSV prevention and management strategy as well. 

Fungal Canker

Drought, flooding and winter injury can leave elderberry plants open to canker-causing fungi. Cytospora, Diplodia, Nectria, Neonectria, and Sphaeropsis spp. are fungi that have been associated with cankers and mortality of the distal end of elderberry canes. Cankers appear on an elderberry as sunken wood or flesh on the trunk or stem. More obvious signs may include wilting or browning of leaves. Prune out infected branches as soon as you notice them to stop the disease from spreading. Remove the entire plant if the canker reaches its trunk.

Powdery Mildew

Powdery mildew is one of the most common and important diseases in ornamentals and fruit trees. It is mainly a problem in shaded, thick and humid areas with poor air movement. Fungus requires a live host to grow and thrive. The presence of a mildew is readily observed at the terminal growth on young and expanding growth. However, it is present on shoots, leaves, buds, flowers and fruit.

Symptoms appear as mycelia (vegetative growth) on the surface of the leaves and as spores (conidia) on the underside of the leaves in the form of whitish-gray structures. These structures resemble flour, hence the name powdery mildew. These lesions spread very rapidly and intensify the problem. The fungus overwinters as mycelium in buds infested in the previous summer. As soon as the buds break open and the new leaves start to emerge, they carry the mycelia that starts to produce spores (conidia). Conidia are carried throughout the shrub and the orchard by wind and land onto the unfolding, developing leaves and new shoots. Rain is not necessary for this disease to spread and develop. High humidity and poor air movement are sufficient for infections to start. 

At the end of the summer when the seasonal growth stops, small, dark, roundish structures start to appear to carry the spores (ascospores) through unfavorable conditions – for example, in cases where there are no remaining hosts. Normally, buds infected with fungal mycelia are less winter hardy and would sustain high mortality at temperatures lower than 15 F below zero.

The best powdery mildew management is to do sanitation by removing infected leaves and to do annual pruning to remove infected shoots and buds. It also helps to thin the shrubs and their crowns. Make them less dense and allow for better air movement, faster drying conditions and better sun penetration.

Verticillium Wilt

Verticillium wilt is a soil-borne disease caused by the fungus, Verticillium dahlia, that can affect more than 350 plant species, including elderberries. Symptoms include general plant decline, wilting (often on just part of the plant) and leaf-edge browning. It does not take long before these branches and shoots die. Making a cross-sectional cut will reveal a streaky discoloration of the conductive tissue below. The color is dark olive green to black. The fungus can build up a very high population on weeds, like lambsquarters, pigweed, ground cherry and nightshade, or on some garden crops, like tomatoes, strawberries, eggplants, raspberries, potatoes and peppers. The fungus enters a susceptible host through its root systems, then continues spreading through the conductive, vascular system. The best control is by avoiding planting on sites where any of the verticillium-susceptible plants were grown. The fungus can survive in its resting structures, microsclerotia, for many years before it encounters a susceptible host and proper environment.

Root Rot

Root rot and collar rot are fungal diseases caused by the fungi from the Phytophthora spp. Plants start declining and showing signs of yellowing, wilting and ultimately dying. The characteristic symptoms are at or just below the soil line. There is an indentation, indicating a canker. Cutting into it will reveal brown to reddish-brown discoloration of a dead, slimy, wet area. Cankers girdle the roots that results in pale foliar coloration, inadequate water and nutrient supply, poor terminal growth, and eventual death. It usually takes about three years before the death of a shrub or a tree. This disease becomes a serious problem where there is poor drainage or frequent flooding. Fungal infections are favored by frequent cool and damp periods. Spending time to select a good, well-drained planting site is the first step in avoiding this problem. Sometimes, tilling will improve the drainage situation. If there is no other option, planting on raised beds will allow the root system to grow above the troubled, poorly drained area. 

Insect repellant and insect growth regulators – We apply a mixture of cold pressed Neem Oil and water to our plants every few weeks to control the harmful insects. TriTek is also a good organic pesticide option.