Roots, Shoots, Fruits & Flowers: Lawn Grubs, Backyard Question, Thirsty Bees and Excessive Phosphorus


A lawn grub on a garden trowel marked in inches. Photo: Lori Dupre.

Lawn Grubs

Lori was working in her yard and found a grub. She sent an email and some pictures, “I found a white grub and would like a more specific identification along with what the resulting beetle would look like along with treatment.”

An insect specialist at the Louisiana State Arthropod Museum identified Lori’s grubs as “the larvae of a scarab beetle.” Some examples of scarab beetles would include June beetles and Japanese beetles. Some treatments would include insecticides like:

  • Sevin™
  • Advanced Lawn Grub Control ™
  • Milky Spore™

Clemson Cooperative Extension shares this report about milky spores, “The most common and widely used biological control of grub worms is milky spore disease. Milky spore disease is a soil inhabiting bacterium (Paenibacillus popilliae) that is ingested by the grub during normal feeding. The bacterium then kills the grub and upon desiccation, the grub will release more bacterial spores into the soil. Milky spore disease is nontoxic to non-target species in the lawn. As with all biological controls, efficacy can be highly variable depending on the site and the environmental conditions at that site.”

Chemical Properties

Chemical formula:(NH4)2SO4

N content:21%
S content:24%
Water solubility750 g/L
Solution pH5 to 6

Basic information about ammonium sulfate. Table:

Backyard Question

Christy emailed her soil test results for her backyard. The results were Very good, and her yard only needs nitrogen and sulfur. One fertilizer would help with both of those plant nutrients, and it is ammonium sulfate. The rate will depend on which turfgrass in Christy’s backyard. Ammonium sulfate will also lower the pH, but in Christy’s case, her pH is a little high.

Christy replied, “Thank you… for taking the time to look at this for me. It is all Greek to me! Do I purchase these at [a local garden center]? Do you know which brand I should get?

Yes, ammonium sulfate would likely be at your garden center. There are plenty of brands: Hi Yield™, American Plant Food™, Lawn & Garden™, Wilco™, etc. Ammonium sulfate is the same regardless of the brand so the best way to buy this fertilizer is to check prices.


A dark Carniolan honeybee sipping water at a fountain. Photo: Kathy Keatley Garvey, University of California Cooperative Extension.

Thirsty Bees

LaDonna shared her concern about bees and wrote, “Since the hurricane we are left with less for the bees and other critters. I have a few bees buzzing around the yard. I made some sugar water for them in a small bowl with pretty rocks. Is this a big “No No”? Am I doing more harm than good? I am sure drinking coke, or any sodas would be worse. Help me help the bees please. I do not want them to die! I would prefer they thrive. Let me know what is best to help the bees until we get flowers and trees.”

Yes, carbonated, sugary drinks would probably also attract wasps and other stinging insects besides honeybees. Beekeepers give their bees a sugar syrup during the winter, so sugar water is Ok. However, LaDonna could also place plain water in a container with rocks or gravel. Her pretty stones will prevent honeybees from drowning.

Bees need water “to dissolve crystallized honey, to dilute honey when producing larval food, for evaporation cooling during warm weather, and for a cool drink on a hot day," according to the California Cooperative Extension.


Excessive Phosphorus

Frank and AHA had visited on the telephone about his recent soil analysis, and Frank sent an email to follow up on this phone visit, “We spoke last week concerning having [excessive] phosphate in my raised beds. I am having trouble finding any fertilizer without [phosphorus] in it. [I] looked at lots of bone meal and they all have some phosphorus. [I] Googled hoof and bonemeal, and all have P, even the unsteamed [bonemeal]. Any suggestions?”

AHA researched some reputable website for sources of fertilizer with high nitrogen and zero phosphorus. Oregon State University Extension Service listed feather meal, seaweed, and urine-soaked stall bedding as good sources of nitrogen without phosphorus. Also, Frank could grow legumes like peas, beans, and vetch to fix N in the soil, and then remove the tops to help with reducing the excess P.

AHA also consulted with George, an Advanced Maser Gardener who tries various organic products in his own garden. George shared these thoughts, “Composted chicken manure would be my choice if I had a high phosphate soil. It is high in nitrogen from Uric acid (white poop of chicken deposits). An Alaskan fish leaf spray is another option.”

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 Also, you can be on the “green thumbs” email list by emailing your request to the address above.

“Before you buy or use an insecticide product, first read the label, and strictly follow label recommendations. Mention of trade names or commercial products in this article is for informational purposes only and does not constitute endorsement by Louisiana State University AgCenter.”

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

3/17/2021 7:46:36 PM
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