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Ask the Experts – August 2017

By Kelly Young

In the seven years we have lived in Arizona, our date palm has never produced dates. Every year, it has flowering stalks but no dates. The plant appears to be healthy otherwise. What could we be doing wrong?

There’s a good chance you aren’t doing anything wrong. I can think of three reasons that you aren’t getting fruits. First, your plant isn’t actually an edible date palm (Phoenix dactylifera). Other palms, such as the queen palm (Syagrus romanzoffiana), or sago (Cycas revoluta) have similar foliage but do not produce edible fruits. Second, you have the right species, but yours is a male date palm, which only produces pollen. Dates only grow on female plants. When the flowering stalk, called the spathe, emerges next spring, notice the color of the flowers. Male date palms produce waxy, white flowers whereas female flowers are greenish-yellow. Finally, you may have a female plant that isn’t getting adequately pollinated by a male plant. Commercial date growers hand-pollinate their plants to ensure abundant production of the fleshy, sweet fruits. You can purchase date pollen online and hand-pollinate your tree yourself.

Our evergreen elm died suddenly last month. The leaves turned brown but are still attached to the stems, which are brittle. Could the cause be Texas root rot?

Unfortunately, you may be correct in your diagnosis that Texas root rot (Phymatotrichopsis omnivora) caused the death of your elm tree. Elms are highly susceptible to this fungal disease, also known as cotton root rot, which is native to Arizona soils. The symptom you described is typical of this disease: rapid death during the summer with leaves still attached. Once the tree has been dead for a few weeks, to accurately isolate and identify the fungus from the dead roots is almost impossible. As a safeguard, avoid planting other species that are susceptible to the disease in the same area. To learn more about Texas root rot, and to find a list of tree species that are tolerant or immune to it, read Dr. Mary Olsen’s publication AZ1150: Cotton (Texas) Root Rot available to download for free at extension.arizona.edu/pubs/cotton-texas-root-rot.

I was pulling spurge weed in my yard and was bitten by dozens of ants, which surged out of the ground near the roots and attacked. How can I get rid of the ants and feel safe in my yard again?

Weedy spurges (Euphorbia spp.) are problematic, during the warm season in Central and Southern Arizona. Fast-growing, these weeds produce hundreds of tiny seeds that are easy to inadvertently spread throughout the landscape. The ants that stung you (they don’t really bite, except to hold on while they viciously sting) were guarding the spurge as their food source. Nectar produced near the tiny flowers is payment to the ants for protection against predators such as you. Reducing the number of spurge plants in your yard will reduce the number of ants. Wear protective gloves and remain vigilant while you pull existing weeds. Dispose of them in the trash, and follow up with an application of pre-emergence herbicide such as Tupersan to prevent new weeds from growing.

Weedy spurges

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