Spotted asparagus beetle on the asparagus sprout top. The main pest of asparagus crop.
O-M-G! For the past 5+years we’ve been growing Asparagus and I’ve been exclaiming how very easy it is to grow… But this year I’ve been proven wrong 🙁 We have a horrible infestation of Asparagus Beetles, the kind with the red spots on their backs.. they eat away at your baby asparagus, opening the tight flower heads, leaving trails cut into the stalks and planting little egg things all over the plants.
We have 2 raised asparagus beds (1) 4ft by 8 ft and (2) 4ft by 8ft which gives us a total of 96 sq/ft of asparagus. The thing about growing Asparagus is it slowly increases in quantity year by year. You can’t even pick any asparagus until year 2 after you planted the crowns! Then year 3 you pick all the asparagus for a week or two then let the ferns grow (they need the top plant to feed the roots lovely vitamin D sunshine! – bigger root system, more asparagus) Year 4, you pick 3-4 weeks, Year 5 you pick 5-6 weeks, etc.. you got the concept right? Each year the roots have grown/expanded and are sending up more shoots. We’ve been enjoying asparagus from our first (smaller) bed for about 4 years now.. the larger bed we started a couple years later so which we just really started harvesting last year… SO It’s a complete bummer when I go out every evening (yes you have to pick asparagus every day or else it flowers and is yucky) that all my beautiful asparagus is chewed up and covered with bugs.. the darn bugs are even eating the tiny ferns that are from very new/young roots… remember if the plant can’t send out it’s solar panels to collect the sunshine it can’t keep growing roots, the plant will die…
I started researching how to kill these Asparagus Beetles, between my gardening books and the internet, the solution is simple, Insecticidal Soap! Great, I thought, I can do that! Look out bugs here I come! Insecticidal Soap is just soap in water… it’s not scientific, it’s not precise.. or so I thought! I grabbed one of my spray bottles, filled it 3/4 of the way with water then added about 1T Seventh Generation Dishwashing Soap gave it a little shake and out the door I went to kill some bugs!
Asparagus Beetles 1, Hayley 0….. I failed. None died, So back to research.. ok so I added more soap 2T and 1T olive oil – oil is supposed to help coat the bug/plant to make it stick better.. Asparagus Beetles 2, Hayley 0.. Failed again… Back to research again… someone swore by Dr Bronners Peppermint soap in their insecticidal soap – Great! I have it.. I started over water, peppermint castile soap and olive oil.. Asparagus Beetles 3, Hayley 0.. this sucks.
Ok, everyone searching for an Organic/Natural solution comes to a point where the question the hassle of the direction they are going.. is this worth it? what is the cost to loosing all this Asparagus? Sometimes I almost wish I didn’t know how bad things like Roundup, Sevin Dust, etc are us and are planet…. times were simple 10 years ago I sprayed weeds with round up and dusted everything with sevin dust, gardening had little frustrations… but I can’t forget what I know and there has to be a solution!! And with complete honestly, I can’t imagine spraying a chemical on my asparagus to kill some bugs with all my chickens standing right next to me.. in the overspray.. looking for bugs and worms all around the asparagus.. breathing and eating such horrible things.. because we eat their eggs and we eat their meat.. I don’t want to eat contaminated meat and eggs or feed them to my friends and family!
Yet again, I set out looking for more ideas to kill these bugs and save my asparagus.. I saw references to cayenne peppers, essential oils, garlic, etc added to insecticidal soap. I decided that I might have to really make up a formula that’s a little more complex that soap in water.. and that’s ok. I’ve come to accept that if it takes some time this year to figure out a fool-proof solution, it will provide me with years of beetle free asparagus…. and I’ve got to admit it’s kinda fun to be a mad-scientist running tests to find a cure! I mixed up a recipe that I thought was covering every option I’ve read about, filled my sprayer and even took some paper plates to collect beetles on and watch them (hopefully) die. It was a success! I found a solution!!!!!
Asparagus Beetle-Killing Insecticidal Soap
Materials
- 3 cups water
- 1 teaspoon crushed red pepper
- 2 cloves galic
- 3 tablespoons Dr Bronner's Peppermint Castile Soap
- 1 tablespoon Cold Pressed Orange Oil Concentrate
Instructions
- Bring the water to a boil, remove pot from burner. Add in the crushed red pepper, garlic-no need to peel, just coarsely slice, soap and olive oil. Let everything marinate until the liquid is cool then fill up your sprayer (don't drain the peppers/garlic out, leave it in) This should be enough to fill a standard spray bottle (roughly 24-30 ounces)
How much olive oil in your asparagus beetle/insecticide spray? I don’t see it listed in the recipe. Thank you!
I mention olive oil as something I tried in my tests, but it is NOT used in my current recipe.
I bought some nematodes, and they should take care of the larvae but I was thinking to use this spray on the adult bugs. Do you know if it would harm the nematodes?
so this is safe to spray right on the asparagus spears while they’re growing (and, following a rinse, not dangerous for us to eat afterwards)?
Yep!
Pretty close to my general insecticide spray. Here is mine – 1T Cayenne pepper, 1/4 C. mouthwash, 1/4 C. Castile Soap, 4-5 cloves garlic, 2T vegetable oil, 1/4 C. baking soda, 5-6 drops of peppermint oil.
I put the garlic, pepper, mouthwash, and baking soda in 1/2 gallon mason jar of water and let steep in the sun for a couple days – sort of like what you are doing with your boiling process. I then add the rest into my 1 gallon sprayer and strain the concentrated brew into it. Fill with the other 1/2 gallon of water and spray away. I use this on all my veggies as a general insecticide and (with the baking soda) fungicide. I suspect it is the pepper that is taking out the asparagus beetles. The garlic tends to ward off adults from landing there to lay eggs – I am trying it on zucchini this year to see if I can keep away the squash borers and squash bugs which take out my crop every year about this time. So far, so good. It is somewhat effective on cabbage and other related veggies but those cabbage moths are very persistent. THis paper says garlic spray as effective as malathion on cabbage moths though…
https://www.researchgate.net/publication/272996610_Use_of_garlic_Allium_sativum_as_a_repellent_crop_to_control_diamondback_moth_Plutella_xylostella_in_cabbages_Brassica_oleraceae_var_capitata
BTW, its important to spray after each major rain event for the preventative effect – unfortunately… as I said those cabbage moths are persistent.
Added benefit – I found it is very effective at keeping deer and bunnies away – makes sense would work on groundhogs as all rely on sense of smell for protection and do not like to browse where it could be masked…
I just captured some wild asparagus and the ferns have beetle larva so they will get sprayed tonight and good riddance!
Wow Thanks so much. This really works and the soap seems popular so I wonder if others are using it too.