Identifying Almond Diseases

Three vs. The Tree

One key to maintaining a productive and profitable almond orchard is being able to recognize and manage trunk and scaffold diseases. Three diseases are of particular concern, says David Doll, a University of California Cooperative Extension farm adviser in Merced. These are botryosphaeria canker, which is rapidly emerging as a serious problem; hull rot, which causes the greatest yield loss; and ceratocystis canker, the most common, but also the most overlooked. Here’s a brief look at each.

1. Botryosphaeria Canker

This fungal disease, also known as band canker, used to be somewhat rare. But now growers are seeing it in both natural openings and pruning wounds in the scaffolds, especially after a rainfall. Spores, which are spread through the air, can come from a wide variety of hosts, as the pathogen is found in many trees in both agricultural and natural settings.

The Padre variety is very susceptible to botryosphaeria, especially when it is growing with high vigor. Incidence in other varieties has been limited. Most commonly, it has been seen in over-fertilized young trees (first through fourth leaf) that are being pushed hard for early production. That is why Doll says it’s being seen more and more. To avoid infection, it’s important not to prune near a rainfall, and avoid large pruning wounds. But if a tree does get band canker, it must be removed. “And when you’re removing it, you must remove the whole tree,” says Doll, “even the stump.”

2. Hull Rot

This is of particular concern this time of year — at hull split. Trees that are over-irrigated and/or over-fertilized are most susceptible to this windborne fungal disease, says Doll. “Dr. Beth Teviotdale (retired Extension specialist) called hull rot the gout of almonds,” he says, “because it can be caused by too much food and water.”

Hull rot is also a big problem because the industry’s most prized variety, the Nonpareil, is one of the most susceptible varieties. To keep your Nonpareils and others from getting it, Doll recommends using a pressure chamber to check your irrigation level this time of year. A fully irrigated orchard will be at minus 10 bars or so, and growers should shoot for a reading of minus 15 bars. “You can help control it through slight water stress at the onset of hull split,” he says. “Studies show that when you induce deficit irrigation, the incidence of hull rot is definitely reduced.”

3. Ceratocystis Canker

 Also known as “shaker’s disease” because it is often caused by injuries that occur from a shaker at harvest, this fungal disease is transferred around the orchard by fruit flies and beetles, which are attracted to a tree’s wound. Ceratocystis canker reduces yield by causing scaffold loss. It is the most common disease of the trunk and scaffold, and can significantly shorten the life of an orchard, says Doll. “It can be a big problem because an orchard will look beautiful from the road,” he says, “but then when you walk through it you see that every branch has some level of ceratocystis.”

Improper harvesting, whether due to bad shaker injury, or shaking too soon after a rainfall or irrigation, are the biggest causes, says Doll. Letting the tree dry down after a rainfall will take care of the latter, while using a good quality shaker will help with the former. “The new shakers will reduce damage to the tree because the pads and the heads are not as rough on the trees,” he says. “I think new technology — as well as the increase in skilled operators — will reduce the problem to a great degree.”

Think Before You Prune

Several times in the past few years, American and Western Fruit Grower has published articles presenting data from researchers that questions the value of pruning almond trees. The trials centered on the main reason growers prune, to increase yields. But in trials up and down the state, University of California Cooperative Extension (UCCE) farm advisers have not found any evidence that pruning increases yields. It’s still somewhat controversial, because it goes against the traditional cultural practice that all deciduous fruit and nut trees should be pruned.

If all the yield data isn’t enough to make almond growers question whether to prune, David Doll, a UCCE farm adviser in Merced, has found that pruning can lead to disease problems. Several pathogenic fungi of almond, including ceratocystis, botryosphaeria, and phytophthora, have caused cankers after gaining entrance through pruning wounds. Doll cautions growers to keep in mind that any time you injure the tree’s cambium layer — such as with a pruning cut — you’re opening up the tree to potential disease problems.

In general, he says that growers should avoid disturbing the cambium layer when the chance of infection is high, which is before or after a rainfall. Because of that, if growers feel they must prune after harvest, they should do so in October or early November, before the state’s rainy season begins. Doll says that he’s finding more and more growers are moving away from pruning, anyway, and he’s not surprised. “Not only do you save on labor, but there’s less disease incidence as well,” he says. “Why waste the money?”

Topics: , ,

Leave a Reply

Nuts Stories
Disease ControlNew Fungicide For Wide Range Of Fruits, Vegetables In California And Florida
April 21, 2015
FMC officially enters biological marketplace with first sales of Fracture fungicide. Read More
NutsPart 2: Spring Weed Management Tips For Almonds: Reduce Herbicide Resistance
April 14, 2015
Follow these tips to help improve long-term efficacy of herbicides. Read More
NutsPart 2: Combating Navel Orangeworm: IPM Approaches to Reduce Pyrethroid Resistance
April 14, 2015
Follow these IPM approaches to reduce unnecessary sprays and manage pyrethroid resistance. Read More
NutsPart 1: Spring Weed Management Tips For Almonds
April 8, 2015
Avoid common weed management mistakes to ensure optimum weed control in the orchard. Read More
NutsPart 1: Combating Navel Orangeworm: Pyrethroid Considerations
April 8, 2015
Proper use of pyrethroids is critical for maintaining the broad-spectrum pesticide’s efficacy. Read More
CitrusCalifornia Snowpack Is Virtually Gone
April 2, 2015
With the lowest water content since 1950, the governor orders first-ever mandatory water reductions in cities and towns, and growers face tighter regulations. Read More
CitrusMake Every Day Ag Day
March 31, 2015
Another National Ag Day came and went on March 18. Did you do anything to promote it this year? Even Read More
The Latest
FruitsOverturned Truck Dumps Millions Of Bees On Highway
April 22, 2015
The truck with 448 hives was headed to a farm in Washington. Read More
CitrusRecord Number Of Organic Producers In U.S.
April 21, 2015
USDA’s Agricultural Marketing Services says domestic production has increased by 250% across all markets since 2002. Read More
FertilizerVerdesian Life Sciences Introduces New Phosphite-Free P…
April 21, 2015
Product designed as alternative for nut and stone fruit growers with concerns about MRLs. Read More
Disease ControlNew Fungicide For Wide Range Of Fruits, Vegetables In C…
April 21, 2015
FMC officially enters biological marketplace with first sales of Fracture fungicide. Read More
NutsPart 2: Spring Weed Management Tips For Almonds: Reduce…
April 14, 2015
Follow these tips to help improve long-term efficacy of herbicides. Read More
NutsPart 2: Combating Navel Orangeworm: IPM Approaches to R…
April 14, 2015
Follow these IPM approaches to reduce unnecessary sprays and manage pyrethroid resistance. Read More
NutsPart 1: Spring Weed Management Tips For Almonds
April 8, 2015
Avoid common weed management mistakes to ensure optimum weed control in the orchard. Read More
NutsPart 1: Combating Navel Orangeworm: Pyrethroid Consider…
April 8, 2015
Proper use of pyrethroids is critical for maintaining the broad-spectrum pesticide’s efficacy. Read More
CitrusCalifornia Snowpack Is Virtually Gone
April 2, 2015
With the lowest water content since 1950, the governor orders first-ever mandatory water reductions in cities and towns, and growers face tighter regulations. Read More
CitrusMake Every Day Ag Day
March 31, 2015
Another National Ag Day came and went on March 18. Did you do anything to promote it this year? Even Read More
Laboratory beakers
CitrusGrowing Demand For Magnesium Nitrate Spurs TradeMark Ni…
March 30, 2015
Via enhancements made to its manufacturing plant, Florida company is able to provide more of its product to various fertilizer distributors and retailers throughout the country. Read More
blue orchard bee
Integrated Pest ManagementBlue Orchard Bee Shows Promise As An Alternative Pollin…
March 30, 2015
The native bee Osmia lignaria could soon be a valuable piece of the pollinator mix, especially for smaller almond growers. Read More
NutsWhy You Should Use Low-Rate Applications Of Potassium
March 26, 2015
These rates provide growers a low-cost method comparable to conventional applications. Read More
Disease ControlBacterial Spot Can Make Almonds Unmarketable
March 24, 2015
Management strategies can help you mitigate losses from this nasty almond disease. Read More
CitrusFarm Bureau Says WOTUS Rule Would Ignore Exemptions
March 24, 2015
Common farming practices may be vulnerable to Clean Water Act enforcement under the rule. Read More
NutsIndustry Update: American Pistachio Growers 2015 Confer…
March 23, 2015
Industry flying high as a billion-pound crop looms at the end of the decade. Read More
CitrusCalifornia Unveils $1 Billion Drought Package
March 23, 2015
Governor, legislative leaders, announce $1 billion emergency drought legislation. Read More
CitrusFeed A Bee Campaign Aims To Plant 50 Million Flowers
March 23, 2015
Bayer CropScience announces program to increase forage opportunities for critical pollinators. Read More