Plant Disease Management Handbook

Cause Pratylenchus penetrans, P. thornei and P. neglectus have been found in established blueberry fields. Root-lesion nematodes are migratory endoparasites with part of the population in soil and part in the roots at all times. Blueberry is not considered a host for these species, which are likely surviving on weed hosts.

See:

Blueberry (Vaccinium corymbosum) - Virus Diseases

See:

Blueberry Cultivar Susceptibility

As berries approach maturity, infected berries become a reddish buff or tan color while mature mummified berries are gray, shriveled, and hard.

Jay W. Pscheidt, 2010.

Mummified fruit that have fallen to the ground. There is not much host tissue left as the fungus has taken the shape of the berry but it is now called a pseudothecium. These will overwinter and develop apothecia in the spring.

Jay W. Pscheidt, 2019.

Numerous apothecia developing from mummified fruit, ready to distribute ascospores to developing shoots and floral clusters.

Jay W. Pscheidt, 2013.

Primary symptoms of mummy berry on a floral cluster.

Jay W. Pscheidt, 2012.

Primary symptoms of mummy berry on a developing shoot.

Jay W. Pscheidt, 2012.

Image related to Blueberry (Vaccinium corymbosum)-Mummy Berry

Infected green berries show no symptoms unless they are cut open. The fungus begins to fill the carpels of the infected berry on the left while seeds form in the healthy berry on the right.

Haywood Photography, 2005.

Here mummified blueberries and brown apothecia are ready to discharge ascospores.

Photo by Jay W. Pscheidt, 1995.

Note the discolored and drying fruit that will soon fall to the ground.

Photo by Jay Pscheidt, 1993.

Cause A soil pH of 4.5 to 5.5 is optimum for blueberry production. Soil pH values significantly outside of this range are associated with a variety of problems. Surveys indicate this as one of the more important problems throughout the blueberry industry. Iron deficiency symptoms are common since iron is less available for plant uptake at high soil pH. High soil pH may occur when a new blueberry field follows other crops that have required the addition of agricultural lime.

These are symptoms of iron chlorosis from inadequate levels of iron due to a high soil pH.

Jay W, Pscheidt, 2008.

The row of yellowed plants in the foreground have high soil pH while the ones in the background are in lower soil pH.

Jay W, Pscheidt, 2008.

Soil pH was too high.

OSU Plant Clinic Image, 2016.

Cause Godronia cassandrae (asexual: Fusicoccum putrefaciens), a fungus. The disease occasionally can interfere seriously with the establishment of new plantings in British Columbia and Washington. It is considered to be the most serious canker disease of blueberry in British Columbia. It is less serious in established fields because only new wood can be infected. However, disease incidence has been increasing in older fields since the late 1980s.

Image related to Blueberry (Vaccinium corymbosum)-Fusicoccum Canker (Godronia Canker)

“Flagging” of branch of a 'Duke' plant infected with Fusicoccum canker.

Dr. Siva Sabaratnam, 2012.

Fusicoccum canker lesions on multiple sites on young stems of a 'Duke' plant near the soil level.

Dr. Siva Sabaratnam, 2012.

Fusicoccum canker lesion developing from leaf scar (left) and Fusicoccum-infected (blighted) flower bud with pycnidia (middle), and fully developed canker with a grey center and reddish-brown margin (right).

Dr. Siva Sabaratnam, 2012.

Infections appear as reddish-brown areas in early spring.

Dept of Horticulture, OSU

Cause The bacteria Agrobacterium tumefaciens has been found in the PNW while A. rubi was reported from Argentina. It is not known if A. rubi, found on caneberries in the PNW, is a problem in blueberry fields in the PNW. Both pathogens survive in soil and infect plants through wounds. Catcher plates on mechanical harvesters can wound canes sufficiently to initiate galls.

Image related to Blueberry (Vaccinium corymbosum)-Crown Gall

Galls can form along the canes and are composed of disorganized parenchyma cells.

Melodie Putnam.

Galls can occur near the root crown as shown on this 'Duke' blueberry.

Maryna Serdani, 2011.

Note the galled tissue along these canes.

Marilyn Miller.

Cause Fruit russeting has been observed with late treatments of chlorothalonil products (Bravo and maybe Echo), Regalia, or triforine (Funginex) at high rates. The russeting can resemble cold injury to fruit. Injury from Bravo is more common when air temperatures are high. The cultivar Bluetta was very susceptible to chemical injury of leaves during 2002 disease control trials in western Oregon.

Image related to Blueberry (Vaccinium corymbosum)-Chemical Injury

Russetted patches on the side of the berry due to late bloom applications of Bravo.

Jay W. Pscheidt, 1993.

Russetted fruit due to late applications of Funginex.

Photo by Jay W. Pscheidt, 1993.

Cause Botrytis cinerea, a fungus that survives as sclerotia (resistant survival structure) and dormant mycelia on dead twigs of bushes and prunings or in fruit left on the bush. It also overwinters as a saprophyte on dead organic matter and dead plant parts in or on the soil surface. Many different fruit (such as blackberry, raspberry, and strawberry) and ornamental crops are susceptible to infection and may be sources of spores.