{"id":2985,"date":"2020-03-28T00:08:33","date_gmt":"2020-03-28T07:08:33","guid":{"rendered":"https:\/\/depts.washington.edu\/hortlib\/pal\/pal-question-611\/"},"modified":"2024-04-13T09:46:16","modified_gmt":"2024-04-13T16:46:16","slug":"treating-peach-leaf-curl","status":"publish","type":"pal","link":"https:\/\/depts.washington.edu\/hortlib\/pal\/treating-peach-leaf-curl\/","title":{"rendered":"Treating peach leaf curl"},"content":{"rendered":"

Have you any advice about how to combat peachtree leaf curl using<\/strong>
\nnatural methods at this stage in the season? I’ve just read about the<\/strong>
\nuse of thyme or oregano oil, but no advice on amount used. I would be<\/strong>
\nglad of any help!<\/strong><\/p>\n

 <\/p>\n

The information I was able to find about thyme oil as a treatment for
\nTaphrina<\/em> came from an application to the U.S. Patents Office<\/a>, so I cannot
\nspeak for its efficacy.<\/p>\n

The U.S. Department of Agriculture’s Agricultural Research Service offers
\nresearch<\/a> on the use of plant essential oils in postharvest disease control, too. My impression is that the efficacy of these plant-based oils is still being studied and evaluated.<\/p>\n

I also found information on managing peach leaf curl (Taphrina deformans<\/em>)[formerly available online] from
\nthe National Sustainable Agriculture Information Service which suggests
\nusing lime sulfur, acceptable by U.S. organic standards, though European
\nstandards may differ. Below is a more substantial excerpt:<\/p>\n

 <\/p>\n

The life-cycle diagram above in Figure 2 shows that the infection period
\nfor leaf curl is when new leaves start emerging from buds in the spring.
\nSpraying after the buds have opened is ineffective, because infection
\ntakes place as the young leaves emerge, and the fungus develops inside
\nthe leaf.<\/p>\n

Accordingly, sprays must be applied during the trees’ dormant
\nperiod after the leaves have fallen and before the first budswell in the
\nspring. Many orchardists spray just prior to budswell during the months
\nof February and March. Orchards with a history of severe peach leaf curl
\nbenefit from a double application: in the autumn at leaf fall and again
\nin late winter or early spring just before budswell.<\/p>\n

Fortunately for the organic grower, lime sulfur is one of the most effective
\nfungicides for control of peach leaf curl and is allowed in certified organic
\nproduction . Bordeaux and copper fungicides are also approved for certified
\norganic programs and are effective as well, but not as effective as
\nlime-sulfur.<\/p>\n

Pscheidt and Wittig (6), performed trials comparing Kocide, lime-sulfur,
\nseveral synthetic fungicides, and Maxi-Crop seaweed for leaf curl
\ncontrol. Lime-sulfur and one of the synthetics (ziram) were best, roughly
\ntwice as effective as Kocide. Seaweed sprays, despite positive anecdotal
\nreports, were completely ineffective.<\/p>\n

Severe leaf curl infection can cause the tree to shed many of its leaves
\nand to replace them with a second flush of growth. At this time the tree
\nwill benefit from a light feeding with a quickly-available soluble
\nfertilizer such as compost tea or fish emulsion to help it recover.<\/p>\n

There are various levels of resistance to leaf curl among varieties;
\nhowever, because of the relative ease of controlling the disease,
\nbreeding for resistance has not been a priority. Redhaven, Candor,
\nClayton, and Frost are some of the cultivars with resistance to leaf
\ncurl, though none is immune. In contrast, Redskin and cultivars derived
\nfrom it are susceptible.<\/p>\n

____________________<\/p>\n

The City of Seattle’s Integrated Pest Management Solutions pages for
\nlandscaping professionals also suggests methods of prevention and
\ncontrol. Damage may be reduced by sheltering the tree from winter and
\nearly spring wet. If only a few leaves are affected, they may be removed
\nby hand. Peach leaf curl does not usually kill the tree, though fruit
\nyield will be reduced. This resource<\/a> also mentions using copper
\nfungicides and lime sulfur when the tree is dormant.<\/p>\n

Fruit–Diseases and pests<\/a>, <\/span>Plant diseases–Control<\/a>, <\/span>Prunus<\/a><\/div>\n","protected":false},"excerpt":{"rendered":"

Have you any advice about how to combat peachtree leaf curl using natural methods at this stage in the season? I’ve just read about the use of thyme or oregano oil, but no advice on amount used. I would be glad of any help!   The information I was able to find about thyme oil as a treatment for Taphrina came from an application to the U.S. Patents Office, so I cannot speak for its efficacy. The U.S. Department of…<\/p>\n

Continue reading Treating peach leaf curl<\/span><\/a><\/div>\n","protected":false},"author":4,"featured_media":0,"menu_order":0,"template":"","keyword":[517,153,250],"class_list":["post-2985","pal","type-pal","status-publish","hentry","keyword-fruit-diseases-and-pests","keyword-plant-diseases-control","keyword-prunus"],"acf":[],"_links":{"self":[{"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/pal\/2985"}],"collection":[{"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/pal"}],"about":[{"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/types\/pal"}],"author":[{"embeddable":true,"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/users\/4"}],"wp:attachment":[{"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/media?parent=2985"}],"wp:term":[{"taxonomy":"keyword","embeddable":true,"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/keyword?post=2985"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}