{"id":224,"date":"2020-03-22T20:00:19","date_gmt":"2020-03-23T00:00:19","guid":{"rendered":"https:\/\/site.extension.uga.edu\/strawberry\/?p=224"},"modified":"2020-03-22T20:00:22","modified_gmt":"2020-03-23T00:00:22","slug":"strawberry-disease-surge","status":"publish","type":"post","link":"https:\/\/site.extension.uga.edu\/strawberry\/2020\/03\/strawberry-disease-surge\/","title":{"rendered":"Strawberry Disease Surge"},"content":{"rendered":"\n

As the coronavirus is wreaking havoc throughout the world, it is hard to get very excited about strawberry diseases \u2013 unless you make an income off strawberries.\u00a0 Unfortunately, the mild temperatures and almost continual rainfall are making it very difficult to manage strawberry diseases at this time. Based on diseases we are currently observing in the field, I will give you a few pointers that may help you to finish up the season as you move forward.\u00a0 <\/p>\n\n\n\n

Anthracnose fruit rot<\/strong><\/p>\n\n\n\n

As it warms up and remains wet, we are seeing anthracnose pop up.\u00a0 We know that resistance has occurred to the strobilurin fungicides (Abound, Pristine, etc.) in many locations throughout Georgia, and therefore, I would not trust these fungicides to control anthracnose \u2013 never at this point.\u00a0 However, even in the absence of apparent resistance (resistance testing conducted and none found), we are seeing severe anthracnose in some locations. The lack of control would then be related to several possibilities: (1) anthracnose having come in on transplants, (2) spray intervals that are less than 7-10 days during rainy weather, and (3) excessive rain and perfect environment for disease.\u00a0 For the remainder of the season, remove and destroy all infected berries (bury them or remove far outside the field).\u00a0 If using strobilurins (Abound, Pristine, etc.), use captan products with them; unsightly residue may be an issue with some captan products, but use these as much as possible.\u00a0 Incorporate Switch and Miravis Prime in the spray program as well going forward. See the IPM Guide for strawberries at www.smallfruits.org<\/a> for additional recommendations. \u00a0<\/p>\n\n\n\n

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Anthracnose of strawberry <\/strong>(photo courtesy of Shane Curry).<\/figcaption><\/figure>\n\n\n\n
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Colletotrichum acutatum <\/em>spores <\/strong>(photo courtesy of Jeff Cook). <\/figcaption><\/figure>\n\n\n\n

Non-infectious phyllody<\/strong><\/p>\n\n\n\n

The leaf growth coming from the fruit below is likely a non-infectious phyllody.\u00a0 There is really nothing to do about it, as these strawberries are hormonally\/physiologically confused.\u00a0 In general, this will work itself out as the season progresses. These symptoms are the same or similar to those caused by Phytoplasmas and some herbicides, but this is not likely the cause of these issues in Georgia at this time.<\/p>\n\n\n\n

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Non-infectious phyllody of strawberry. Fruit are forming leaves which is indicative or hormonal issues. <\/strong><\/figcaption><\/figure>\n\n\n\n

Phythopthora root and crown rot<\/strong><\/p>\n\n\n\n

We are seeing quite a bit of this disease due to the wet\nconditions observed recently. Phytophthora crown and root rot is caused by Phytophthora cactorum<\/em>. The source of the\ninoculum is oospores which persist in soil or infected plants. Under wet\nconditions, oospores produce zoospores, and these mainly infect wounded plant\ntissue (root or crown). Wet conditions likewise encourage the spread of the\npathogen from plant to plant. Infected transplants are a major source of\ninoculum in fumigated beds. Wounds can be induced during the transplanting\nprocess, and this also increases infection. Control measures are generally\nlimited to use of chemical fungicides. Ridomil Gold SL can be applied through\ndrip irrigation systems at 1 pt. per treated acre in sufficient water to move\nthe fungicide into the root zone. Ridomil Gold SL contains a systemic compound,\nand root uptake is critical to activity. Make one application after\ntransplanting, followed by an additional application 30 days before the\nbeginning of harvest or at fruit set. A third application may be made during\nthe harvest season. In order to avoid illegal residues, do not use more than a\ntotal of 1.5 quarts of Ridomil Gold SL per treated acre per year. <\/p>\n\n\n\n

Phosphonates, such as Aliette WDG or ProPhyt or many others,\nare also registered for use on Phytophthora\ncactorum<\/em>, but the labels may specify leather rot control, as opposed to\nroot and crown rot. These are also registered for red stele (Phytophthora fragariae<\/em>). Phosphonates\nhave systemic activity when foliar applied, and this systemic activity should\nhelp with root and crown rot as well, but Ridomil is generally more active when\nthe disease is observed. Ridomil Gold SL is really the best choice if\nresistance has not occurred. If using phosphonates, read the labels for\ninstructions, as labels differ across products. <\/p>\n\n\n\n

Leaf blotch <\/strong><\/p>\n\n\n\n

Leaf blotch has been observed in multiple locations this\nyear. Leaf blotch is caused by Gnomonia<\/em>\nspp. (anamorph Zythia fragariae<\/em>).\nThis is a relatively rare strawberry disease, but persistent cool wet weather\nwill allow for significant infections, and we have had these conditions often\nin the last couple of months. Fungicides that are active against Phomopsis\ngenerally have activity against this disease as well. Apply Rally + Captan a\ncouple of times for this, about 14 days apart. <\/p>\n\n\n\n

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Leaf blotch of strawberry.<\/strong><\/figcaption><\/figure>\n\n\n\n
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Zythia fragariae<\/em> conidial spores<\/strong>. <\/figcaption><\/figure>\n\n\n\n

Angular leaf spot<\/strong><\/p>\n\n\n\n

Angular leaf spot (bacterial) has also been observed.\nAngular leaf spot of strawberry, caused by Xanthomonas\nfragariae<\/em>, can be suppressed by use of copper sprays (copper hydroxide or\ncopper sulfate products). Copper hydroxide products may be more efficacious\nthan copper sulfate products for this pathogen. Discontinue use when\nphytotoxicity appears, usually after 4-5 applications.<\/p>\n\n\n\n

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Angular leaf spot of strawberry<\/strong> (photo courtesy of Jeff Cook).<\/figcaption><\/figure>\n\n\n\n
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Oozing bacterial lesions from angular leaf spot<\/strong> (photo courtesy of Jeff Cook).<\/figcaption><\/figure>\n\n\n\n

That pretty much covers it for now.  We are seeing lots of disease for sure.  Keep in mind that the various diagnostic\nclinics are closed for business at this time, so diagnostics are limited at the\nmoment to digital images.  Please\ncontinue to work with your local county agents to communicate your needs.  I pray you will all stay well, and though\nmany questions remain to be answered, I hope you have a productive season.  <\/p>\n","protected":false},"excerpt":{"rendered":"

As the coronavirus is wreaking havoc throughout the world, it is hard to get very excited about strawberry diseases \u2013 unless you make an income off strawberries.\u00a0 Unfortunately, the mild temperatures and almost continual rainfall are making it very difficult to manage strawberry diseases at this time. Based on diseases we are currently observing in […]<\/p>\n","protected":false},"author":125,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-224","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/site.extension.uga.edu\/strawberry\/wp-json\/wp\/v2\/posts\/224","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/site.extension.uga.edu\/strawberry\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/site.extension.uga.edu\/strawberry\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/site.extension.uga.edu\/strawberry\/wp-json\/wp\/v2\/users\/125"}],"replies":[{"embeddable":true,"href":"https:\/\/site.extension.uga.edu\/strawberry\/wp-json\/wp\/v2\/comments?post=224"}],"version-history":[{"count":3,"href":"https:\/\/site.extension.uga.edu\/strawberry\/wp-json\/wp\/v2\/posts\/224\/revisions"}],"predecessor-version":[{"id":235,"href":"https:\/\/site.extension.uga.edu\/strawberry\/wp-json\/wp\/v2\/posts\/224\/revisions\/235"}],"wp:attachment":[{"href":"https:\/\/site.extension.uga.edu\/strawberry\/wp-json\/wp\/v2\/media?parent=224"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/site.extension.uga.edu\/strawberry\/wp-json\/wp\/v2\/categories?post=224"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/site.extension.uga.edu\/strawberry\/wp-json\/wp\/v2\/tags?post=224"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}