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Three common fungal problems in blueberry production

August 21, 2020

Blueberries on a blueberry bush will reach maturity at different times.

From your breakfast smoothie to savory dishes, blueberries have a much greater versatility than their small size might convey. In order for that blueberry to get to your kitchen, growers of this labor-intensive crop must face the many challenges of berry production. After ensuring the presence of the acidic soil that various blueberry cultivars prefer, as well as ensuring that the variety used fits into the location’s growing season demands, the battle against environmental and disease pressure begins. A slew of diseases attack blueberry bushes, but the fungal diseases that attack the leaves, branches and flowers of the plant are some of the more common problems that directly affect the plant’s yield and its ability to continue to be a viable plant for future harvests. 

A few of the most common diseases that affect blueberries include botrytis, mummy berry and anthracnose. These diseases, which proliferate during the times of the year that are more humid, spread when infected material comes into contact with healthy growth. Rain and irrigation help with this transmission, either by directly depositing disease spores onto the bushes or by creating a wet environ that nests the infection and fosters more favorable conditions for spreading.


Commonly called grey rot, this disease is caused by the fungus Botrytis cinerea. Signs of botrytis include blossoms that have turned brown, appear to have a grey powder and begin to die off. This fungus can be spread by the wind and via water splashed from infected blossoms and foliage, and it can lay dormant on pruned branches and plant debris from previous cuttings. Botrytis poses the greatest threat to the plant at some of its most susceptible growth stages: bloom and right before harvest.

One of the most important steps to take for botrytis control in blueberries is to plant bushes that are spaced far enough apart to allow for sufficient air flow. Drip irrigation is preferred in order to keep the aerial parts of the plant dry. Prune and remove infected and damaged twigs.

Mummy berry disease

Another fungal disease that makes flowers turn brown and die off, mummy berry disease also produces blackened marks on leaves that eventually wilt and die. Mature fruit that is Infected will become grey and hard and will fall off the bushes before harvesting time. 

Since this disease can be transmitted to healthy flowers through pollinating insects, wind and rain and can be transferred to new growth through fallen infected berries, one of the more effective ways to combat mummy berry disease is to keep the fallen infected berries from being able to access the plant. This can be accomplished by removing or burying mummified berries from under and around the plant by cultivating the soil underneath the bushes. While time consuming, harvesting and destroying mummified berries before they drop to the ground can be very effective for mitigating infection.


Plants infected with ripe rot, or anthracnose, may not show any symptoms until after harvest. This is a tricky disease that spends the winter months hiding in infected twigs, older growth and live buds. New infections occur in humid conditions, when rain and irrigation can transfer spores, most often between the flowering and berry development phases. If any symptoms manifest prior to harvest, they will appear near the time of berry maturation, and a few flowers may wilt and turn brown, or the flower part of the berry may soften. The greater danger with anthracnose comes during post-harvest, when berries are packaged and stored; salmon-colored spores will appear on the berries and spread to other berries in the same package.

Mitigation strategies for anthracnose are similar to those for botrytis: Separate bushes to create more space between each plant; drip irrigate; and increase the air flow in the plant through pruning. Additionally, quickly move harvested fruit to cold storage.  

Growers can also use fungicides to help limit the spread of these diseases. However, with the future of many fungicides in question, what else can growers do to help their blueberry bushes? Once the practices that create physical barriers for fungal infections, such as plant spacing, have been implemented, the focus should turn to the plants themselves. After planting and during the growth phases, it is important to ensure that the plant’s nutritional needs are met. Well-nourished plants are more capable of resisting environmental and disease pressures.

Growers can complement their existing fungicide programs with biostimulant nutritional aids, such as AGRO-MOS, maximizing plants defense mechanisms.

Benefits of Agro-Mos:

  • Based on nutrigenomic research
  • Proper nutrition aids in reducing overall plant stress
  • Complements existing pest-management programs while avoiding residues


Find out how Agro-Mos can be beneficial in your berry production!