Tips To Identify Bacterial Diseases On Stone Fruit [Slideshow]

Both bacterial spot and bacterial canker are destructive bacteria that infect stone fruit. Let’s take a look at some of the predisposing factors to infection, symptoms to watch for, and tips to help you avoid problems in your orchard this year.

Bacterial Spot
Symptoms limit yields and in some cases, 100% fruit loss has been observed. Bacterial spot can be confused with the fungal disease peach scab, however the symptoms are different.

Unfortunately, there are few effective controls for bacterial spot. Cultivar susceptibility in early bud break and early fruit ripening can favor the occurrence of bacterial spot. Sandy and clay soils also predispose trees to this bacterial disease. Disease is favored by hot, humid, and wet conditions. Wind and wind-blown sand can increase the severity of bacterial spot by creating wounds for bacteria to enter.

Bacterial Spot Management
There are two primary strategies for bacterial spot management. One is to plant bacterial-spot-resistant cultivars. These cultivars are not immune to the bacteria, so control measures will still need to be applied especially if there is high disease pressure and susceptible cultivars are planted nearby.

The other management strategy is using chemical control. Copper can be applied; however, there is a risk of phytotoxicity and resistance. Growers can also apply oxytetracycline, which is often applied as many as 10 times during a season if disease conditions persist. The risk with oxytetracycline is possible antibiotic resistance, persistent yield loss, and label imitations.

Bacterial Canker
Bacterial canker is most problematic on sweet cherry varieties. This is a cold-weather disease, with epidemics seen most in cold, frost-prone areas in the spring. This infection limits tree life and productivity and is caused by several bacteria. Losses due to fruit lesions are sporadic. The infection moves into the trunk and limits production and causes tree decline.

Some of the predisposing factors that favor the occurrence of bacterial canker include the training system, cultivar and rootstock susceptibility. Trees planted with the Modified Central Leader and Spanish Bush are most susceptible, whereas the Perpendicular V system is the least susceptible. Bacterial incidence is likely in sweet cherry cultivars such as Sweetheart and Lapins. Bing has also shown to be susceptible. Gisela rootstock is highly susceptible to bacterial canker.

Soils with nutrient deficiencies, including a low nitrogen rate, low soil pH (below 5.5), and high nematode populations can favor the occurrence of bacterial canker.

The bacteria produce proteins that increase the freezing temperature of water. Consequently, when bacteria are on the surface of the plant, frost damage can occur thereby predisposing the plant to disease since the bacteria feeds on the nutrients released by the injured plant tissue. During bloom, bacterial populations increase 10 to 100-fold. Autumn rains and cooler temperatures can cause higher rates of bacterial colonization, and infection at leaf scars can be high. When trees are exposed to severe temperatures, the chance for infection increases.
Winter pruning may also cause bacterial canker.

Bacterial Canker Symptoms In Fruit
Sporadic symptoms may be seen, including water damage with soaked lesions, brown lesions, and spots.

Bacterial Canker Management
Management of bacterial canker includes keeping trees healthy. Remove and prevent plant stressors by maintaining adequate nutrients and soil pH. Control nematodes in the soil. Plant trees in well-drained soils. Weeds support bacteria populations, so keep weed populations low. Remove wild Prunus. Old trees are a source of bacteria; do not inter-plant new trees with old trees.

Reduce bacteria before trees enter susceptible periods. Copper sprays such as a Bordeaux mixture with Canola oil (2.8 quarts Canola oil per 100 gallons) may be applied in the spring as well as September, October, and November to help reduce bacteria bacterial populations.

Avoid large, dormant cuts when pruning. Minimize the impact of disease with summer pruning. Keep in mind the 12-inch rule with stub pruning, distancing infection from the main trunk.

Topics: , , , ,

Leave a Reply

Fruits Stories

FruitsSexual Evolution May Bear More Fruit In The Orchard
October 30, 2014
Scientists take a closer look at genes and find new plant breeding possibilities. Read More
Apples & PearsWashington Apples To Restart Shipments To China
October 29, 2014
Agreement reached between U.S. and Chinese governments to reinstate market access after two-year absence. Read More
EquipmentEnter To Win A Kubota At The Washington State Horticultural Association Annual Meeting
October 29, 2014
Attendees have a chance to take home a new utility vehicle courtesy of Wilbur-Ellis and Western Fruit Grower. Read More
CitrusUSDA To Provide $4 Million For Honey Bee Habitat
October 29, 2014
The funds will go toward helping growers implement conservation practices to improve honey bee health. Read More
FruitsHuge California Drought Meeting Planned
October 29, 2014
State, federal officials to meet as forecasts for the coming year look bleak. Read More
FruitsValent U.S.A., MGK Enter Into Marketing Agreement
October 28, 2014
Valent U.S.A. to manage the marketing and sales of MGK’s crop protection line of insect control products beginning in April 2015. Read More
FruitsMichigan State Offers Online Database Of Tree Fruit Diseases, Insects
October 28, 2014
Search engine helps growers identify several issues in the orchard. Read More

The Latest

CitrusForecast: South Florida Dry Season May See Fair Share O…
October 31, 2014
Outlook calls for possible above-normal precipitation around region for fall and winter months. Read More
FruitsCalifornia Growers Sue State Over Drought
October 30, 2014
They claim the State Water Resources Control Board illegally denied water deliveries. Read More
FruitsSexual Evolution May Bear More Fruit In The Orchard
October 30, 2014
Scientists take a closer look at genes and find new plant breeding possibilities. Read More
EquipmentEnter To Win A Kubota At The Washington State Horticult…
October 29, 2014
Attendees have a chance to take home a new utility vehicle courtesy of Wilbur-Ellis and Western Fruit Grower. Read More
CitrusUSDA To Provide $4 Million For Honey Bee Habitat
October 29, 2014
The funds will go toward helping growers implement conservation practices to improve honey bee health. Read More
FruitsHuge California Drought Meeting Planned
October 29, 2014
State, federal officials to meet as forecasts for the coming year look bleak. Read More
FruitsValent U.S.A., MGK Enter Into Marketing Agreement
October 28, 2014
Valent U.S.A. to manage the marketing and sales of MGK’s crop protection line of insect control products beginning in April 2015. Read More
FruitsMichigan State Offers Online Database Of Tree Fruit Dis…
October 28, 2014
Search engine helps growers identify several issues in the orchard. Read More
CitrusModern Agriculture Is A True Centerpiece Of Thanksgivin…
October 27, 2014
FFAA's Mary Hartney says take time during this holiday season to give thanks where thanks is due. Read More
CitrusNOAA’s Winter Weather Outlook Runs Hot And Cold
October 27, 2014
Repeat of last year’s extreme cold and snow events east of the Rockies unlikely. Read More
FruitsBig Bucks Given To Grow Better Fruit Crops
October 27, 2014
Two projects to be focus of five-year, $10 million grant from USDA. Read More
Farm ManagementBill Gates Uploading Lots Of Florida Farmland
October 22, 2014
Recent acquisition for the Microsoft icon involves more than 4,500 acres for nearly $28 million. Read More
FruitsAnnual Santa Maria Strawberry Meeting Approaching
October 22, 2014
The meeting will focus on IPM practices, weed management, updates on fumigation, and more. Read More
Farm ManagementUSDA Awards $18 Million To Stimulate Research And Devel…
October 22, 2014
The grants will provide resources to help small operations create breakthroughs, says USDA Secretary Tom Vilsack. Read More
CitrusEPA Launches Program To Reduce Pesticide Drift
October 22, 2014
The voluntary star-rating program aims to protect people, wildlife and the environment. Read More
CitrusMcCrometer Introduces New Ag Management Mobile App
October 22, 2014
The app displays data on weather, ET, soil moisture, water flow, and more. Read More
CitrusAgriculture, Interior Departments Partner To Measure Co…
October 22, 2014
Goal is to provide science-based information for watershed wellness. Read More
CitrusIt’s Time For Young Farming Leaders To Engage [Op…
October 21, 2014
Florida Grower editor Frank Giles says there are capable and talented youths in the ag field ready to step up and take the reins. Read More