Asparagus is a perennial crop that should have a productive life of 15 or more years. Asparagus spears grow upward through the soil from underground crowns. The spears are cut by hand every 2-5 days. After two to three months, spear harvest ceases and the spears are allowed to grow into ferns with a thick canopy of feathery leaves. During the fern stage, the plant produces and stores energy for the following year’s crop. Purple spot on asparagus was first reported in the U. S. in 1981. The main damage from purple spot is on fern growth. Fungal damage to the ferns results in defoliation of the needles which reduces the flow of carbohydrates to the roots and lowers next years yield.
“Purple spot of asparagus is an important fungal disease in many growing regions including Michigan, California, Washington, England, and New Zealand. The fungus overwinters as pseudothecia on the surface of asparagus fern debris and releases ascospores as primary inoculum in the spring.
Purplish lesions may subsequently develop on the spears, making them commercially unacceptable, especially for the fresh market… Following infection, tan to brown lesions may develop on the fern and premature defoliation may occur. Premature defoliation of the fern limits its photosynthetic ability, resulting in decreased carbohydrate reserves for the crown that may negatively affect yields in the following years.
Growers apply fungicides to manage purple spot on the fern after the last spears are harvested; fungicides are not applied to asparagus spears that will be harvested.”
Authors: Granke, L. L., and M. K. Hausbeck.
Affiliation: Department of Plant Pathology, Michigan State University
Title: Influence of Environment on Airborne Spore Concentrations and Severity of Asparagus Purple Spot.
Source: Plant Disease. 2010. 94:843-850.
Brown Rot on Peach
The brown rot fungus infects all the acres of cherries, peaches and nectarines in the U. S. Ash-gray masses of millions of spores appear on the fruit and the fruit becomes completely rotten and soft within a few days. Brown rot caused substantial fruit losses before the development of fungicides. Most peach growers expected to lose 50-75% of their crop. With the development of a finely-powdered sulfur fungicide about 1912, stone fruit growers began widespread spraying to control brown rot. This spraying has continued to this day.
“Who does not love the delicious taste of fresh peaches, nectarines, plums, apricots, or cherries? Because of their popularity, stone fruits are grown all over the world, but it is not only consumers who like these tasty fruits. Some fungi have specialized in infecting and colonizing stone fruits wherever they are grown.
There are ways to reduce disease pressure in commercial orchards, including the removal of fruit mummies from the tree canopy, pruning out cankers and removal of wild plums surrounding orchards. However, these measures do not prevent brown rot disease, and growers are still dependent on the application of fungicides for blossom blight and pre- and postharvest disease management.”
Authors: Schnabel, G., et al.
Affiliation: Clemson University.
Title: Sustainable brown rot management of peaches in the southeastern United States.
Source: Outlooks on Pest Management. 2010. October. Pgs. 208-211.
Brown Rot on Peaches
The University of California’s IPM Guidelines list 37 fungicide products available for controlling diseases in peach orchards. Major flower, foliar and fruit diseases of peach include peach leaf curl, shot hole, brown rot, powdery mildew and rust. The key is to select the best fungicide product with the broadest spectrum of activity against these pathogens and time the application at a critical stage.
“Fungicides are the most effective and safe way for managing diseases of cling peach. Fortunately, there are numerous choices because multiple fungicides with different modes of action (MOA) are registered for each disease. This may appear to make a decision more difficult, but having multiple active ingredients available allows for competitive pricing, development of highly effective management programs that target problematic diseases at individual orchard sites, and resistance management. …In recent years, many active ingredients have become available as generic products under different trade names. This has further increased the complexity but also allows for reducing fungicide costs to the grower.”
Author: Adaskaveg, J. E.
Affiliation: UC Riverside
Title: Effective and Economical Management of Flower, Foliar, and Fruit Diseases of Cling Peach
Source: Orchard Notes. January 2014. Pgs. 2-4.