Black spot - Grapes

Elsinoe ampelina

Black spot, also known as anthracnose in grapes, is a serious disease, particularly in areas which experience cool wet springs which favour disease outbreak. Currently it is successfully managed with fungicides, however prior to their introduction, blackspot was a major problem. Table grape varieties including sultana and red globe are more prone to black spot than wine grapes. Once established black spot is unrelenting and regular treatments are required to manage it.

Refer to links below for more information on black spot in other crops.

Description

Small (1-3 mm) dark brown to black round lesions appear on leaves, eventually a hole develops at the lesion site appearing like a ‘shot hole’, and infected leaves appear distorted. Shoots develop white to grey lesions with a defined dark margin and severe infections can cause the shoot to break or prevent bunches forming.

Small, brown sunken spots develop on fruit, later developing into lesions with grey centres and dark red margins. Severely affected immature fruit is either shed or remains attached as shrivelled mummies. Major crop losses can occur from severe infections, particularly when inoculum levels are highest after reoccurring wet spring conditions.

Black spot survives as sclerotia in stem cankers from the previous year’s infection, and spores can remain in cankers for 3-5 years. Spring rainfall spreads spores onto young leaves and shoots which are most commonly infected. For infection to occur, foliage needs to remain wet for greater than two hours.

Control

It is vital to reduce overwintering lesions to prevent the build-up of black spot. Infected leaves, shoots and mummied fruit clusters should be removed and destroyed.

Vineyards known to have black spot should be monitored early in the season. In addition, planting resistant varieties may help control where black spot is an issue.

A preventative approach to control is important when black spot is known to be present, as young leaves and shoots are susceptible. Early season application of a fungicide at budburst followed by another 10-14 days later is suggested.

Related Pests

Mango bacterial black spot

Xanthomonas campestris pv. mangiferaeindicae

Bacterial black spot (BBS) was first found in Australia in the early 1980’s and it now appears in most northern mango growing areas of Australia. It has the potential to be a serious disease of mangos, in some cases up to 90 per cent of fruit is discarded due to spots on fruit deeming them unacceptable for market.

Refer to links below for more information on black spot in other crops.

Blackspot of field peas

Mycosphaerella pinodes, Phoma mediccaginis var. pinodella, Phoma koolunga, Ascochyta pisi

Commonly referred to as ascochyta blight, blackspot is one of the most serious diseases of field peas and is widespread in Victoria and South Australia. In field peas, blackspot is produced by four different pathogens, producing symptoms that are indistinguishable from each other. Yield losses of up to 60 per cent have been reported, particularly in wet seasons.

Refer to links below for more information on blackspot in other crops.

Black Spot Tomatoes and Potatoes

Alternaria solani

Black spot, also commonly known as early blight or target spot, is a serious fungal disease affecting vegetables belonging to the Solanaceae family. Disease hosts include tomatoes, potatoes, capsicums and eggplants. Outbreaks are favoured by warm, wet growing conditions and yield losses can be significant.

Refer to links below for more information on black spot in other crops.

Black Spot Apples and Pears

Venturia inaequalis (Apple scab), Venturia pirina (Pear scab)

Black spot, also known as apple scab or pear scab, is a serious disease found in pear and apple growing regions across Australia. Whilst symptoms in apples and pears are similar, the disease is caused by different fungi and cross infection from one host to the other isn’t possible. Leaves and fruit at early development are highly susceptible and serious yield and quality reductions are likely if not managed properly, especially in wet seasons.

Symptoms in pears and apples are very similar and therefore have been described as such unless otherwise indicated.

Refer to links below for more information on black spot in other crops.

References

CABI (Viewed Oct 2019), ‘Grape Anthracnose’ Plantwise knowledge bank, CABI, https://www.plantwise.org/knowledgebank/datasheet/20773#PreventionAndControlSection

Taylor, A and Gordon, C (2019), ‘ Black spot of grapevines in Western Australia’, Department of Primary Industries and Regional Development (DPIRD), https://www.agric.wa.gov.au/spring/black-spot-grapevines-western-australia?page=0%2C1

Whiting, J (2010), ‘Black spot of grapevines’, Agriculture Victoria, Department of Environment and Primary Industries VIC, http://agriculture.vic.gov.au/agriculture/pests-diseases-and-weeds/plant-diseases/grapevines/black-spot-of-grapevines