Mystery Weeds? Giant Leather Fern, Free Herb Class

Get help identifying garden mystery weeds. Free Landscape Matters class on herbs being offered Nov. 9, 2011 in Yulee by Master Gardener. Giant Leather Ferns can reach heights of 12 feet and are cold hardy for northeast Florida.

EDITOR’S NOTE: University of Florida/IFAS Extension Director for Nassau County and Environmental Horticulture Agent III, Rebecca Jordi, addresses questions about landscaping and gardening in northeast Florida. She is also a University of Florida faculty member.

___GARDEN TALK Q & A ____

Creeping Cucumber, Garden Talk, Nassau County Florida Extension
Creeping Cucumber (photo by Jeffrey Pippen)

QUESTION: I found this weed growing in the soil I had delivered for my fall garden. It looks like tiny watermelons but the leaf looks like a cucumber. BM

JORDI: I have had three people bring this weed in to me within the last 2 weeks. I was fortunate in contacting the Duval County Commercial Extension Agent, Erin Harlow, and she was able to identify it for me immediately. You most likely have the weed called creeping cucumber, Melothria pentula. I found it interesting that most of the specimens of this weed showed evidence of the disease powdery mildew on the leaves. The leaf does indeed look like a cucumber and the speckled, melon-like fruit is about the size of a pecan. Creeping cucumber also produces a small yellow flower similar to cucurbit flower.

Some of the educational sources I consulted about this plant stated the fruit was not for human consumption although some wildlife may use it for food. There are some indications creeping cucumber may harbor the watermelon mosaic virus (WMV) and papaya ringspot virus (PRSV). It would therefore be important to remove the weed whenever it is located around vegetable or fruit gardens. If the weed had the virus, it can easily be transmitted to other plants by one of the piercing/sucking insects such as aphids or whiteflies. This is a good example of why it is important to keep gardens weed free.

[box type=”tick” style=”rounded” border=”full”]On November 9, 2011 at 10 am, Master Gardener, Claudie Speed, will conduct a free Landscape Matters class on herbs open to the public. The session will take place in the conference room main building at the James S. Page Governmental Complex. Claudie will discuss herbs that can be grown for both culinary and medicinal purposes. The herb bed in the Demonstration Garden will have a variety of herb plants. For more information, see the Nassau County, Florida Extension website or call the Extension office at 904-879-1019 or 904-491-7340.[/box]

QUESTION: Can you identify this weed for me? It has spread all over my flower beds. JT

Spreading Dayflower photo
Spreading Dayflower

JORDI: It would have been somewhat difficult without the flower, but since you brought in a nice section of the weed along with the blue flower I was able make a better determination of the plant.

Spreading dayflower, Commelina diffusa, is commonly found in ditches and in low areas where water might accumulate. Of course, this weed can also be found in landscapes receiving too much water. This weed is particularly troublesome as it can carry the virus responsible for cucumber mosaic virus disease (CMV). This virus is found throughout the world and can infect many plants in the cucurbit family such as cucumber, squash, cantaloupe, tomatoes and peppers.

If you find creeping dayflower, it would be best to remove it or chemically treat it with an herbicide to keep it in check. Aphids feeding on the dayflower can easily transmit the virus from the weed to the food crop. The symptoms can be mild in which there may be slight, twisted formations of leaves to whole plant stunting and reduction of fruit production. In the landscape, the growth habit is somewhat similar to crabgrass but the stems are more succulent. It is often confused with doveweed but the blue flower makes it easy to distinguish. The good news – it does not tolerate foot traffic, compacted soil or mowing well. I think the best advice in a flower bed is to pull it manually and consider reducing the amount of water the flower bed receives.

Giant Leather Ferns Can Grow to 12 Feet in Height
Giant Leather Ferns Can Grow to 12 Feet in Height. Cold Hardy for Northeast Florida

QUESTION: What can you tell me about the giant leather fern? Can we grow it here? CB

JORDI: Giant leather fern, Acrostichum danaeifolium, can indeed be grown here as it is suitable for cold hardiness zones 8b through 12. Remember we, in Northeast Florida are 8b (west part of the county) – 9a (east part of the county). It can reach heights upward to 12 feet which is why it gets the name giant fern. It has been used along retention ponds as it can tolerate fresh to brackish water. This fern can be grown in full sun but will look better in partial shade. Too much sun will cause the edges of the leaflets to turn brown causing people to assume it is dying. Old fronds need to be removed periodically to keep a fresh look. It also does not tolerate drought well, which means it would need weekly irrigation.

Rebecca Jordi

Rebecca L. Jordi
County Extension Director
UF/IFAS Environmental Horticulture
Nassau County Extension
543350 U.S. Highway #1
Callahan, FL 32011
904-491-7340 or 904-879-1019

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