Anthracnose (Drepanopeziza ribis) and Septoria Leaf Spot (Septoria ribis = Mycosphaerella ribis)

Hosts

Currants and gooseberries.

Damage

These fungal diseases cause yield loss and reduce vigour of susceptible varieties in wet seasons. Disease is more severe in wet seasons. Infected leaves yellow and drop in mid-season.

Symptoms

Small, dark brown, angular or round spots appear on leaves, petioles and flower stems. Spots contain tiny, black or grey fungal fruiting bodies visible in wet weather. On currants, anthracnose can also cause “fly-speck” spots on fruit. Infected fruit may crack open and drop.

Disease cycle

These fungi over winter on dead leaves, fallen fruit and twigs on the ground. In spring, airborne spores infect new leaves at the base of the bush. Three to four weeks later, spores produced on these leaves spread in water droplets to upper leaves.

Monitoring

Watch for the first spots on lower leaves in spring. By the time symptoms are seen on upper leaves, the disease is usually widespread.

Management

Cultural control

Grow disease-resistant varieties. Most newer commercial varieties have some resistance.

Prune bushes and control weeds and grass to improve air circulation. Irrigate so that leaves dry off before night-fall.

Rake up and destroy fallen leaves to remove the over wintering fungus.

Cultivate between rows to bury fallen leaves in fall or before bud-break in spring.

Chemical control

If the disease was a problem the previous season, apply fungicide sprays in the spring. Start when the first new leaf is fully open, and repeat as long as wet weather continues. Post-harvest sprays applied in the fall may also help to to reduce over wintering inoculum.

Bordeaux Mixture 8-8-100. Apply when foliage is dry. Do not apply during fruiting, as may leave a visible residue; or

Copper 53W (copper sulphate) at 3 to 5 kg/ha (1.2 to 2 kg/acre) in 1000 L of water. Add 4 kg of hydrated lime per 1000 L. Do not apply more than 4 times per season. Do not re-enter treated fields within 48 hours of application. Do not apply within 2 days of harvest; or

Proline 480 SC (480 g/L prothioconazole) at 315 mL/ha (126 mL/acre) in enough water to obtain good coverage. Apply at the first sign of disease. Repeat 10 to 14 days later if conditions remain favrouable for disease.  Do not apply more than twice per year. Do not apply more than 820 mL/ha (328 mL/acre) per crop per year. Will provide suppression of Septoria only. Do not apply within 7 days of harvest; or

Inspire Super (86 g/L difenoconazole, 249 g/L cyprodinil) at 836 to 1161 ml/ha (338 to 470 ml/acre). Apply before symptoms appear when conditions are conducive for disease. A second application may be made 10 to 21 days later. Apply in a minimum of 200 L/ha (81 L/acre) of water. Do not make more than two applications per crop per season.  Do not apply within 1 day of harvest; or

Sercadis (300 g/L fluxapyroxad) at 250-666 mL/ha (100-266 mL/acre) in enough water to obatin good coverage.  Apply prior to onset of disease development. Spray in rotation with fungicides from other groups on a 7 to 14 day schedule.  Use the shorter spray interval when disease pressure is high. Do not apply more than 3 times per crop season. Can be applied up until the day of harvest; or

Currants only:

Ferbam 76WDG (76% ferbam) at 6.75 kg/ha (2.7 kg/acre). Do not apply within 14 days of harvest.

Note: Ferbam is registered on currants only. Ferbam is not acceptable to all markets. Check with your packer before using.

Blister Rust (White Pine Blister Rust) (Cronartium ribicola)

Hosts

Currants, gooseberries and white (5-needle) pine (Pinus monticola, Pinus strobus).

Damage

Defoliation may occur on susceptible varieties, but often has little impact on yield. Some black currant varieties, such as Ben Alder, and most gooseberries are susceptible to rust. Ben Sarek, Tiben and Ben Connan are less susceptible but will develop some disease. Titania and Tisal are immune. Resistance breaking rust strains have been detected in other areas, but it is not known whether they are present in BC. Red currants are usually less affected.

White pine is killed by this fungus. Do not plant any susceptible varieties of Ribes within 300 m (1000 ft.) and preferably 1 km from any white (5-needle) pine. Do not grow currants, other than immune varieties such as Titania, in white pine forest areas such as eastern Vancouver Island or the southern Interior valleys.

Symptoms

Small raised, orange pustules of the fungus develop on the underside of infected leaves. These are usually clustered in large yellow leaf spots, which may be visible on the top and bottom of the leaf. Brown, hair-like growths may develop in the spots from early spring through fall. Heavily infected leaves yellow and drop.

Disease cycle

Currant and gooseberry leaves become infected by airborne spores (aeciospores) from pines in the spring. Each spore produces a group of pustules on the underside of the leaf. Pustules produce orange urediospores which infect more leaves until the fall. The hair-like growths are columns of dark orange to brown teliospores. When these germinate they appear to have been dipped in icing sugar, as they produce white basidiospores. Most Basidiospores are released in late summer and are spread by wind to infect white pines.

Monitoring

Check for the appearance of pustules on the underside of leaves from spring through summer.

Management

Cultural control

Plant immune or resistant varieties (see variety reccommendations). Remove ornamental 5-needle pines within 300 m (1000 ft) of the field.

Chemical control 

Nova (40 % myclobutanil) at 340 g/ha (135 g/acre) in enough water to obtain good coverage. Apply at the first sign of disease and repeat 7 to 14 days later. Pre-bloom, bloom, and immediately after bloom are the most critical times for the control of white pine blister rust. Do not apply more than 3 times per season. Do not apply within 6 days of hand harvest.  Do not apply within 1 day of mechanical harvest.  

Botrytis Fruit Drop, Fruit Rot And Blight (Botrytis cinerea)

Damage

The fungus, Botrytis, may cause significant yield loss on currants especially if wet weather occurs during bloom, fruit ripening or harvest.

Symptoms

Infections occurring during bloom may cause flowers to blight and fruit to drop prematurely. Shoots may also be infected resulting in blight and die-back.

Disease Cycle

Botrytis is a very common fungus. It over-winters on branch tips and on dead twigs or organic debris on the ground. In the spring, masses of spores are produced on this material and carried by wind currents to new growth. Blossoms, twigs and fruit may be infected under periods of high relative humidity and cool temperatures.

Monitoring

Examine twigs for symptoms of infection. Alert pruners to symptoms of twig infection and attempt to prune these out where possible. Watch for blossom infections particularly during periods of wet weather.

Management

Cultural Control

Improve air movement in the field by adequate pruning.
Avoid high levels of nitrogen which promotes excessive leaf growth.

Avoid planting in areas subject to spring frosts as frost-damaged tissue may encourage infection and spread.

Biological Control

None

Chemical Control

Protect blossoms with fungicide sprays applied at the start of bloom. Repeat sprays as required particularly in wet conditions. To delay development of resistance, alternate the products listed below. Never apply fungicides from the same group more than twice in succession.

Group 3/ Group 9

Inspire Super (86 g/L difenoconazole, 249 g/L cyprodinil) at 1033 to 1475 ml/ha (418 to 597 ml/acre) starting at early bloom or when conditions are conducive to disease. A second application may be made 10 to 21 days later. Apply in a minimum of 200 L/ha (81 L/acre) of water. Do not make more than two applications per crop per season for Botrytis. Do not use more than 5.9 L/ha (2.4 L/acre) per crop per season.  Do not apply within 1 day of harvest; or

Group 7

Lance WDG or Cantus WDG (70% boscalid) at 560 g/ha (224 g/acre) in enough water to obtain good coverage. Apply beginning at early bloom. Spray in rotation with other fungicides on a 7 to 14 day schedule. Use the shorter interval when disease pressure is high. Do not apply more than 4 times per season. Do not make more than two consecutive applications of Lance or Cantus. Lance or Cantus can be applied up to the day of harvest; or

Sercadis (300 g/L fluxapyroxad) at 250-666 mL/ha (100-266 mL/acre) in enough water to obatin good coverage.  Apply beginning at early bloom, prior to onset of disease development. Spray in rotation with fungicides from other groups on a 7 to 14 day schedule.  Use the shorter spray interval when disease pressure is high. Do not apply more than 3 times per crop season. Can be applied up until the day of harvest; or

Note: Sercadis will only provide suppression of Botrytis 

Group 7/11

Pristine WG (25.2 % boscalid, 12.8 % pyraclostrobin) at 1.3 to 1.6 kg/ha (0.52 to 0.64 kg/acre) in enough water to obtain good coverage. Apply beginning at early bloom. Spray in rotation with other fungicides on a 7 to 14 day schedule. Use the shorter interval when disease pressure is high. Do not apply more than 4 times per crop per season. Do not apply Pristine or other products containing Group 7 or 11 fungicides more than twice in succession. Do not re-enter treated fields for hand harvesting within 24 hours of application. Do not re-enter fields for all other activities until residues have dried. If mechanical harvesting, application can be made up to the day of harvest.

Group 9/12

Switch 62.5 (cyprodinil/fludioxonil) at 775 to 975 g/ha ( 310 to 390 g/acre). Make the first application at early bloom and repeat at 7 to 10 day intervals. Do not apply more than 3 times per season. Do not make more than 2 consecutive applications of Switch. Alternate with other fungicide groups to prevent development of resistance.  Do not apply within 1 day of harvest.  

Group 17

Elevate 50 WDG (50% fenhexamid) at 1.7 kg/ha (0.7 kg/acre) in enough water (up to 1000 L/ha) to obtain good coverage. Apply up to 4 times per season beginning at early bloom. Do not make more than two consecutive applications of Elevate. It should be alternated with other fungicide groups to prevent development of resistance. Do not apply within 1 day of harvest; or

Biofungicides

Serenade Max (14.6% Bacillus subtilis) at 3.0 to 6.0 kg/ha (1.2 to 2.4 kg/acre). Begin applications at the first sign of disease or when conditions favour disease development. Repeat as necessary on a 7-10 day interval. Serenade may be applied up to and including the day of harvest

Note: Serenade is a bacterial-based biofungicide. It is approved for organic production.

Powdery Mildew (Sphaerotheca mors-uvae and Sphaerotheca macularis)

Hosts

S. mors-uvae is more commonly found on Ribes in the Pacific Northwest. It attacks currants, gooseberries and ornamental Heuchera. S. macularis has a very wide host range including strawberries, raspberries and many weeds and flower crops.

Damage

Infected fruit is unmarketable due to the fungal coating, and may be discoloured, or crack and rot. Severely affected plants are stunted.

Symptoms

A white or greyish, powdery growth appears on leaves, green shoots and fruit. Later, this changes to a brown coating containing tiny, black specks, which are the fungal fruiting bodies. Infected currant fruit are often small and pale-coloured.

Disease cycle

The fungal fruiting bodies over winter on fallen leaves and fruit. Airborne spores infect new leaves and fruit every year in late spring, usually near the start of bloom. Warm, humid weather and late-season dew and fog favour mildew development.

Monitoring

Check leaves for the first signs of white, powdery growth before and during bloom.

Management

Cultural control

Plant resistant varieties. See variety descriptions.

Prune bushes and control weeds for good air circulation.

Cultivate between rows in fall to bury infected leaves.

Chemical control

On susceptible varieties apply sprays every 7-14 days in spring to protect emerging foliage and young fruit.

Bordeaux mixture 8-8-100. Apply when foliage is dry. Do not use near harvest as it may leave a visible residue.

Microscopic Sulphur WP (92% sulphur) at 5 kg/ha (2.0 kg/acre). Apply at 10-14 day intervals from the onset of disease until fruit colouring. Sulphur may burn foliage when temperatures are above 32o C during or within 3 days of application. Apply in sufficient water to obtain good coverage. Do not use more than 8 sprays per season. Do not apply within 1 day of harvest.

Sulphur 80% DF (80% sulphur) at 31 kg/3000 L of water. Begin at pre-bloom stage or when disease first appears and repeat at 7-10 day intervals. Do not allow spray drift onto sensitive plants. Sulphur may burn foliage when temperatures are above 32o C during or within 3 days of application. Do not apply within 21 days of an oil treatment. Do not apply within 1 day of harvest.

Pristine WG (25.2 % boscalid, 12.8 % pyraclostrobin) at 1.6 kg/ha (0.64 kg/acre) in enough water to obtain good coverage. Apply beginning at early bloom. Spray in rotation with other fungicides on a 7 to 14 day schedule. Use the shorter interval when disease pressure is high. Do not apply more than 4 times per crop per season. Do not apply Pristine or other products containing Group 7 or 11 fungicides more than twice in succession. Do not re-enter treated fields for hand harvesting within 24 hours of application. Do not re-enter fields for all other activities until residues have dried. If mechanical harvesting, application can be made up to the day of harvest; or

Nova 40W (40 % myclobutanil) at 340 g/ha (136 g/acre) in enough water to obtain good coverage. Apply at the first sign of disease development and repeat in 7 to 14 days. Do not apply more than 3 times per season. Do not apply more than two consecutive applications of Nova or Mettle fungicides. Do not apply within 6 days of harvest if hand picking or 1 day of harvest if picking by machine. Do not allow re-entry into the field for 8 days for hand setting of irrigation lines and 6 days for training and hand harvest activities; or

Gooseberries only:

Lime Sulphur (23% calcium polysulphide) at 15 L/1000 L of water at the green tip stage before earliest flowers open, and again at the calyx stage. Later sprays may result in visible residue on fruit. Do not apply when foliage is wet or when temperature is above 27o C. May cause yellowing and defoliation on some varieties, or if applied at calyx without an earlier application at green tip stage; or

Mettle 125 ME (125 g/L tetraconazole) at 219 to 365 mL/ha (88 to 146 mL/acre) in enough water to ensure thorough spray coverage. Begin applications when disease first appears or when conditions favour disease development. Repeat applications as required at 14 to 21 day intervals. Do not apply more than two consecutive applications of Mettle or Nova fungicides. Do not apply more than 2 times per season. Do not use within 14 days of harvest.