Roots, Shoots, Fruits & Flowers: Peach Leaf Spot, Pecan Pests, Homemade Chemical Fertilizer, and Small Cucumbers

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Peach leaf with entomosporium leaf spot. Photo: Blake Jones

Peach Leaf Spot

Blake J. sent an email with some very clear pictures and he wrote, “Your name came up on my parish AgCenter site. I hope you can help identify a problem I am having with some peach trees. Small red spots form on the leaves, gradually get bigger, after the leaves are mostly red, they fall off. I am going to attach some pictures so that you can see what is going on. I have Florida king, Florida Crest, and Rio Grande peach varieties. Thank you for your time.”

Blake J has Entomosporium leaf spot (ELS), and according to the AgCenter website shares this information about ELS, “[This leaf spot is] caused by the fungus Entomosporium mespili (formerly E. maculatum), is a common disease of various woody ornamentals in the [rose family]”.

“Several fungicides can be helpful in the management of Entomosporium leaf spot, including products with chlorothalonil, myclobutanil, propiconazole or tebuconazole as the active ingredient. Begin fungicide applications as soon as new growth is evident during the spring and make repeat applications every 10 to 14 days until hot weather sets in. Additional applications may be necessary during the fall if weather conditions are suitable for disease development.”

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Pecan leaves with insect damage by phylloxera.
Photo: Cathy Farris

Pecan Pests

Cathy sent a desperate message, “Hey [AHA]! Can u help me out here.... spots on pecan tree leaves????”

Cathy has pecan phylloxera on her leaves. These insects cause a gall which serves as a brood chamber for juveniles.

Treatment by homeowners is very difficult because the pecan buds need to be treated between bud development and leaf expansion. Also, the ability to spray by homeowners may be limited. Commercial pecan growers have the expensive equipment to treat for this insect. Fortunately, phylloxera infestations of homeowners’ pecan trees are merely nuisances.

Homemade Chemical Fertilizer

Fred asked a very good question about homemade fertilizers, “There are recipes for homemade Miracle Gro™ on the internet using ammonia, baking soda, Epsom salt and water. I am thinking this is not going to give you a Miracle Gro™ fertilizer. What is your take on it?”

AHA emailed to Fred, “You are correct that the ingredients will not make MG equivalent. Miracle-Gro Water-Soluble All-Purpose Plant Food ™ has a ratio of 24-8-16, which means that it contains 24 percent nitrogen, 8 percent phosphorus and 16 percent potassium, as expressed in the national standard format.

Ammonia provides nitrogen, baking soda has sodium bicarbonate, and Epsom salts have magnesium. This homemade fertilizer will be nutritionally incomplete when compared to Miracle Gro™. I have concerns that these ingredients will burn plant roots, although Epsom salts are beneficial for magnesium deficiency.”

Also, these homemade chemical “fertilizers” may change soil pH so plants cannot absorb them. The best homemade “fertilizers” are made from organic materials composted at home, not mixed with household chemicals.

512_fig_3_small_cucumberjpgEarly cucumber on the vine.
Photo: Lee Rouse, LSU AgCenter

Small Cucumbers

Margo asked a question about her vegetable garden, “I have three cucumber plants, [and] they have tons of flowers the bees are doing their job. I have four little in cucumbers, and they have been like that for a week or more. [They are] not producing. What am I doing wrong or what can I do [to] help?”

If the cucumbers are otherwise healthy, then the best answer would be low soil temperatures. The best soil temperature for cucumber growth to start would be 64 degrees F. The recent cool temperatures may have prevented the soil to warm up enough to enable the growth of cukes. Apparently, the soil temperatures were warm enough for germination and then cooled to cause stagnation of the small cukes.

If you want to contact Roots, Shoots, Fruits and Flowers, please send your questions and pictures to Keith Hawkins, Area Horticulture Agent (AHA), 337-463-7006 or khawkins@agcenter.lsu.edu. Also, you can be on the “green thumbs” email list by emailing your request to the address above.

“This work has been supported, in part, by the USDA National Institute of Food and Agriculture, Renewable Resources Extension Act Award, Accession Number 1011417.”

5/12/2020 6:36:46 PM
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