by Matt Lollar | Jun 4, 2018
Normally we think of rust as something that deteriorates metal, but a number of different fungal rusts can affect plants in the garden. Rust disease can affect corn plants, cedar trees, and even blueberry bushes. Just like the broad range of plant species that can be plagued by rust, there are a number of species of rust fungal spores floating around and ready to infest your garden. This article will focus on leaf rust of blueberry.
Blueberry leaf rust on the top of a leaf. Photo Credit: Philip Harmon, University of Florida/IFAS Extension.
Leaf rust of blueberry in Florida is caused by the fungus Pucciniastrum vaccinii. Although the common name of the disease is “leaf rust”, the disease can also infect the stems and fruit of blueberry plants. The disease causes small, round spots visible on the tops of leaves. Spots will multiply and the leaves will eventually yellow and fall off. Young stems and green fruit can also become infected as the disease progresses. Bright orange lesions will form on stems and fruit as the thousands of microscopic spores conjoin. The clusters of spores are easily wiped or washed off of plant material. When spores dry out, they become airborne and can be transferred to nearby plants.
Blueberry leaf rust on fruit. Photo Credit: Philip Harmon, University of Florida/IFAS Extension
The rust fungus thrives in hot, humid, wet conditions. A number of cultural practices can be adopted to reduce disease progression and survival.
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Irrigation
Disease persistence can be reduced by limiting the amount of water that contacts the plant leaves. Water the base of plants or install drip irrigation for your bushes rather than watering from overhead. If overhead irrigation is the only option, then water plants in the morning rather than in the evening. This allows the leaves to dry out over the course of the day.
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Pruning
Removal of approximately 25% of the oldest canes in late winter before spring growth begins will stimulate the production of new canes and should result in plants with canes of different ages and will provide a good mix of vigorous branching and fruit production. Moderate summer pruning can also improve yield and shoot growth. When pruning, cut out vigorous shoots that are growing well beyond the desired canopy height and are in the interior portion of the bush. This will promote a more open growth habit and help with air circulation on the remaining plant material. Some vigorous canes developing from the ground and growing on the outside of the bush can be topped to stimulate branching and flower bud formation.
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Mulch
Pine bark mulch helps with establishment of young plants and helps keep soil pH low in existing plantings. A layer of aged pine bark 3 inches deep extending about 2 feet out from the plants will provide a good growing medium for surface feeder roots. Pine straw can be used if pine bark is unavailable. Mulch also moderates soil temperature, helps keep weeds at bay, and adds organic matter to the soil. Make sure to keep mulch raked back about three inches away from the plant canes to provide good air circulation to the roots.
Hopefully this article has given you some tips to have a good blueberry crop for years to come. For more information on growing blueberries in Florida, please visit the University of Florida/IFAS EDIS Publication: Blueberry Gardener’s Guide.
by Roy Carter | Jun 10, 2014
Blueberry. Photo credit: Eric Zamora, UF IFAS.
Blueberries are native to Eastern North America. They are one of the few crop plants that originated here. The rabbiteye blueberry occurs mostly in certain river valleys in Northern Florida and Southeastern Georgia. The high bush blueberry is native to the eastern third of the United States and Southeastern Canada. Florida is rich in other native species. The woods and swamps of Florida are populated with at least eight wild blueberry species. No area of the state lacks wild blueberries, except where soil pH is above 6.0.
The two types of blueberries grown in Florida are Southern highbush and rabbiteye. The earliest ripening southern highbush varieties ripen about 4 to 6 weeks earlier than the earliest rabbiteye varieties grown at the same location.
Some rabbiteye varieties recommended for our area are: Alice blue, Beckyblue, Climax, Bonita, Brightwell, Chaucer and Tifblue. Some recommended Southern Highbush varieties are: Blue Crisp, Gulf Coast, Jewel, Sharpblue, Santa Fe, Star and Misty.
Blueberries need a fairly acid soil; a pH range of 4 to 5 is suggested. Blueberries grown on alkaline or deep sands will grow poorly. If you need to lower the soil pH before planting, mix in some acidic peat moss.
Blueberries have a shallow, fibrous root system. That means plants should be placed in the ground about an inch deeper than they were growing in the nursery. Rabbiteye blueberries grow poorly in soils with excessive drainage. But they won’t tolerate too much moisture for long periods of time either.
Blueberries are very sensitive to fertilizers. During the first growing season, no mineral fertilizer should be added at all. In the second season, apply about two ounces of an acidic fertilizer per plant. Blueberries can use the same fertilizer as camellias and azaleas, but be careful not to overdo it. Excessive amounts of fertilizer will kill the plants.
Before planting blueberries, you should cultivate the soil by plowing or roto tilling to a depth of at least six inches. Dig a hole large enough so that the roots won’t be crowded. Lightly pack the soil around the roots and water thoroughly. Keep in mind that newly set plants need a good water supply.
Bare-root bushes should be transplanted during the winter months; container grown bushes can be transplanted anytime. The first year after planting, the blossoms should be removed to help the bush grow more quickly.
Pruning is an important part of blueberry culture. It promotes the growth of strong wood, and rids the tree of weak twiggy growth. The strong wood growth is necessary for good fruit production.
Believe it or not, the worst pests of blueberries are birds. You need to protect your bushes with some kind of netting, or employ the old fashioned scarecrow to do the job. It you don’t protect your bushes, you can count on the birds getting to the fruit before you do.
Other than birds, rabbiteye blueberries have few pest or disease problems. Powdery mildew can occur on bushes that don’t get full sun, but this problem can be easily controlled with a sulfur spray. Bud mites, thrips, fruitworms, and defoliating insects can sometimes be a problem.
Weeds will compete with young blueberry bushes for nutrients and water, so keep the beds as free of weeds as possible. Mulches are good for controlling weed growth. If necessary, there are herbicides available.
For more information please see:
Blueberry Gardener’s Guide
by Matthew Orwat | Oct 23, 2013
Image Credit: UF IFAS EDIS
From Dr. John P. Hayes”
“Florida Crossroads made a 28 minute video entitled “Seeds of Change” featuring the IFAS breeding efforts to create new varieties of blueberries, strawberries, tomatoes, and other crops, and the ways that these programs have influenced Florida industry.
For those of you who are familiar with our breeding programs, you’ll enjoy seeing some of our scientists on the screen. For those who aren’t familiar with IFAS development of new varieties, it is well worth the watch and I’d encourage you to do so. Our breeding program and the scientists engaged in breeding at UF are world class.”
by Julie McConnell | Jul 1, 2013
Blueberries
Have you tasted the great local blueberries available this season? Want to start your own Blueberry garden? Now that Blueberry harvest is in full swing in the Florida Panhandle, it is a good time to discuss blueberry culture.
Blueberry plants in garden centers lure us in with bell shaped flowers or especially if already setting fruit. Before you take one home, make sure your site is suitable. Doing your homework before you plant is important, but especially so when you want to grow a plant with specific cultural requirements such as blueberries. Blueberries require well-drained acidic soil that contains organic matter, a minimum of 4-5 hours of sunlight daily, and space away from competing roots. Chill hour requirements and bloom time vary by blueberry types.
Soil in the Florida Panhandle has a wide pH range (measure of acidity) and can vary greatly even within a half-acre site. Having your soil tested prior to planting is critical to growing blueberries successfully because it is very difficult to lower pH if your soil is higher than the target range. Blueberries need acidic soil (pH 4.2-5.5) to be able to use micro-elements in the soil such as iron and zinc. As the pH increases, these nutrients become less available to the plant even if they are present in the soil in adequate quantities. Nutrient deficiency leads to weak plants and loss of vigor. Plan to test your soil before you purchase plants to ensure your site has the ideal pH range, visit your local UF/IFAS County Extension Office to obtain a soil test kit. For more details about how soil pH affects your landscape, please see EDIS SL256: Soil pH and the Home Landscape or Garden.
Sandy soils commonly found in North Florida tend to be low in organic matter. Incorporating soil amendments directly into planting beds or using mulches that decompose (such as pinestraw or wood mulch) will help increase organic matter in your landscape. Peat moss or pine bark can be incorporated into beds planned for blueberries or pine bark can be used as mulch. Adding organic matter will help retain soil moisture, which is beneficial to blueberries that have shallow root systems.
Retaining soil moisture is valuable to blueberries, however, the site does need to drain well to a minimum depth of 18 inches. Areas that remain wet for long periods of time increase the risk of Phytophthora root rot damage. If an otherwise ideal site does not drain well, consider building a raised bed or changing the location.
Four to five hours a day is the minimum sunlight needed for good blueberry production. Make sure your sunny site is at least 20 feet from building foundations and competing tree roots. Blueberry plants can get large, over ten feet in height and width! Plan to give them room to grow; with pruning they can be maintained around 7’x7’.
There are two main types of blueberries that grow well in Florida: the southern highbush and rabbiteye. Among those types, there are specific cultivars with low chill requirements that perform better in Florida than in other southern states. Rabbiteye blueberries are recommended for areas north of Ocala, southern highbush for central and south Florida. When choosing cultivars, you need to plant at least two different cultivars within the same type (rabbiteye with rabbiteye) and make sure that bloom time overlaps so that cross pollination can take place.
Rabbiteye cultivars recommended for the Panhandle are:
Early season
• ‘Beckyblue’
• ‘Bonita’
• ‘Climax’
Mid- to late-season
• ‘Brightwell’
• ‘Powderblue’
• ‘Tifblue’
• ‘Woodard’
• ‘Chaucer’
• ‘Bluegem’
For more information about blueberry site preparation, selection, pest management, and care please see EDIS CIR1192 Blueberry Gardener’s Guide.
