Flowers Against Aphids – The Research Continues

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September-sown Borage flowering in our hoophouse in January. Photo Pam Dawling

It’s late November as I write this. Starting last fall (2021) we sowed a range of flowers to attract beneficial insects, to plant in our hoophouse in hopes of reducing the early spring aphids. Aphids can get out of control in early spring in our greenhouse and hoophouse, as they become active before their native predators, such as ladybugs, emerge from hibernation. In January we get bad aphids on the lettuce and, of the flowers we planted to attract beneficials, borage was the only one flowering. It was not enough. We did three sprays of soapy water at 5 day intervals to kill the aphids. We also have a particular problem in our hoophouse and in our greenhouse on the eggplant, pepper and tomato transplants from mid-April to mid- to late- May depending when we manage to get them under control.

Young eggplant struggling against lots of aphids.
Photo Pam Dawling

Most flowers in our trials were annuals, and they flowered and died. We still have four yarrow plants and one bushy shungiku. Shungiku is Glebionis coronaria, (formerly called Chrysanthemum coronarium, Ismelia coronaria, Xanmthophthalmum coronarium, or Pinardia coronaria), and commonly called Crown Daisy. Most chrysanthemums are perennial with poisonous leaves, but shungiku is an annual. Our plant seems not to know this.

September-sown shungiku (chrysanthemum greens) in January.
Photo Pam Dawling

Shungiku is the eastern Japanese name for the edible chrysanthemum, also known as “garland chrysanthemum” or “chop suey greens” in English. It is known as “Kikuna” in western Japan, “tong hao” in Chinese, ssukgat in Korean and cải cúc or tần ô in Vietnamese. There are various colors of flowers. Ours are yellow, not banded with other colors. We bought seed from Small House Farm. Bevin Cohen says it does attract bees, butterflies and predatory insects, and would probably do well in the winter hoophouse, and could be provoked into bolting early in the spring.

After our research and trials, we decided it isn’t worthwhile growing the annuals, as they didn’t flower when we needed them (except this shungiku!). We might try borage again, as it was quick to flower last year, and other people have done well with borage. Ours died. We also decided (as recommended by a reader) to leave some overwintered brassicas to flower. We are starting to find bolting mizuna, so that may be perfect.

Bolting mizuna in our hoophouse
Photo Pam Dawling

Two of the four yarrow plants have flowers (in November) and we will keep them. Having perennials seems a good way to get flowers in early spring. These plants were too young to flower last spring. We still have some seeds of the perennial phacelia, so we could try that again, although perhaps it isn’t cold-hardy enough.

Anti-aphid yarrow flowering in our hoophouse in late November, 13 months after sowing. Photo Pam Dawling

If you want to read the trials and research that led us to this point, see two posts from February 2022: More on Insectary Flowers. It was too cold for predators in early February, even with enticing flowers. Ladybugs showed up in late February and we had borage flowers for them, but no other flowers. We had sowed at the very beginning of September and the very end of October. After that, we started more flowers in our greenhouse on February 1. We noticed that plants in pots dry out very fast in the hoophouse, and they have to be hand-watered, as the drip tape doesn’t do it. It’s probably better to get the flowers in the ground in the hoophouse and greenhouse as soon as they are big enough.

Earlier in February, I posted Growing flowers to attract aphid predators in early spring

I listed aphid predatory insects such as ladybugs, lacewings, aphid parasites, damsel bugs, braconid wasps, rove beetles, syrphid flies, and spined soldier beetles, as are attracted to plants with small flat open flowers, like alyssum, dill, yarrow, buckwheat, sunflowers, and cosmos.

On a big scale this is known as Farmscaping, and you can read about it in a publication from ATTRA; Farmscaping to Enhance Biological Control . You can use this publication to make a specific plan to tackle particular pests. Ladybugs are a good general help because they eat the eggs of many different pest species.

A ladybug on the leaf stem of a sunflower planted to attract beneficials. Photo Pam Dawling

Organic Integrated Pest Management involves tackling pest problems one step at a time with ecologically-based practices, starting with actions chosen to reduce the chances of the pest ever getting a grip on your crops. You can find various listings of steps online and in print. They are all in basic agreement – start with prevention, follow with avoidance, and finish with pest-killing if needed. I recommend the ATTRA Organic IPM Field Guide. Each of the 22 pages is a poster, complete with good photos and concise clear info.

eOrganic has many articles on Insect Management in Organic Farming Systems that explain ways to tackle pest problems with ecologically-based practices, starting with actions chosen to reduce the chances of the pest ever getting a grip on your crops.

A pepper leaf with tiny aphids.
photo Pam Dawling

That post describes the lifecycle of aphids, starting in spring with eggs hatching into wingless females that give birth via parthenogenesis to more females. Within a week, one female can produce 100 clones, which can repeat the process at the age of one week.  This continues until adverse weather or predators trigger production of a generation of winged female aphids that moves to new plants. Later in summer male aphids are born and females lay fertilized eggs that overwinter on host plants, to hatch the following spring.

There is a chart in the post, giving details of the flowers we chose, where we found the seed, and which months we decided to plant them in.

Our first sowing, in September, was of borage and shungiku (Chrysanthemum greens) only. We thought having some flowering plants in large pots would enable us to move them to the trouble spots, but plants in pots dry out too fast. The borage flowered with pompom-like clusters, much more compact than spring outdoor borage does.

Anti-aphid flowers yarrow in pots in January (October sown)
Photo Pam Dawling

The second sowing, in late October, included Meadowfoam, Tidy Tips, Phacelia and Yarrow. Those plants were still small at the beginning of February. No flowers, no help against January lettuce aphids.

The third sowing was February 1, and included borage, shungiku, Meadowfoam, Phacelia, Tidy Tips and yarrow.

The September-sown borage and shungiku both had trouble with cold temperatures during January – three non-consecutive nights at 10F (-12C). Some of each got cold-damaged.

By February, no beneficial insects had been seen on the borage flowers, and no aphids had been killed as a result.

Shungiku in November with a bee.
Pam Dawling
Shungiku with spider, in November. Pam Dawling
Shungiku with a fly in November. Pam Dawling
This looks like a leaf-footed bug on the shungiku in November. Not good news to have this pest around! Pam Dawling

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The background to these 2022 trials included a lot of research. In July 2021 I posted Controlling Aphids in Early Spring

Climate change is making the problem worse: for every 1degree Celsius rise in average temperature (about 2 F degrees), aphids become active two weeks earlier.

Organic Integrated Pest Management

I have a blog post about our organic integrated pest management, a 7 step method of pest management which starts with actions least harmful to the ecosystem, only employing biological controls such as botanical sprays and selective pesticides if necessary after all other steps have been insufficient.

Pepper plant with aphids and ants farming them.
Photo Pam Dawling

Applying these principles to dealing with early spring aphids

  1. Prevent infestation Control ants (which farm aphids for their sweet excretions). Try repellents, or trap crops of nasturtiums.
  2. Cover or protect physically with fine mesh netting.
  3. Provide habitat for natural enemies. Plant for a continuous supply of insect-attracting blooms, that flower early in the year and attract predators such as ladybugs, lacewings, syrphid flies (hoverflies), damsel bugs, big-eyed bugs, and spiders. Grow early flowers with pollen and nectar they can use as alternative foods. Sow seed in fall for earliest bloom.
  4. Monitor crops at least once a week
  5. Introduce natural enemies: We do have an aphid parasite in the hoophouse as we do find mummies, but not enough to control an aphid outbreak in spring. Parasitic wasps for aphids include Aphidus colemani from Arbico Organics; Aphidus ervi from Arbico; a predatory gall-midge, Aphidoletes aphidomyza, (cost $125 including shipping per week, perhaps $375 total); Green Lacewings (more affordable); Ladybugs, notorious for flying away.
  6. Hand pick and kill. Handpicking aphids is likely impossible, so blast them off the plants with a water jet from a hose.
  7. Use biological controls. Failing success with the methods above, a soap spray can be effective, although aphid predators will also be harmed. We use 3 Tablespoons (15 ml) per gallon (3.8 l) of biodegradable Murphy’s Oil Soap, in a sequence of 3 sprayings 5 days apart.

Also see that post for details about Tidy Tips (Layia platyglossa), a spring flowering wild annual in the aster (sunflower) family; Meadowfoam (Limnanthes douglasii), a fast-growing bushy annual commonly known as poached egg plant and Douglas’ Meadowfoam; Baby blue eyes (Nemophila menziesii), a low spreading, shrub-like annual; Borage, a warm-season annual, taking only about 8 weeks to flower from sowing; Sweet Alyssum, a small annual; Shungiku, described above. We considered, but did not plant two biennials: Dill and Angelica, as they sound quite large. The perennials we chose, are also large (30” tall, or much more, and might need staking), but the advantages of having permanent working plants won us over. Yarrow is hardy to zone 5. Common Yarrow (with flowers that range from white to red) is hardy down to zone 3. It attracts an array of beneficial insects. Phacelia is particularly useful in early spring if it has overwintered as it is an early pollen source for bees coming out of hibernation. Sow in the fall for early spring blooms But it winter-kills at approximately 18˚F (-8˚C), and I think that’s what happened to ours. We also considered Fennel, Foeniculum vulgare (common fennel) but it blooms from mid-summer to frost. Too late and too tall for our goal of attracting spring aphid predators in the hoophouse. Coyote bush, (Baccharis pilularis), also called chaparral broom, is a native shrub related to sunflowers, that sounds way too much of a space hog. And Dandelions – I just couldn’t bring myself to risk planted this sturdy weed in the hoophouse!

That post also includes details of natural enemies you can buy, and how to make a soap spray if none of those efforts work. Also there you will find the approach we decided on as the Best Options for our Hoophouse and Greenhouse in April and May

November photo of shungiku flowering in our hoophouse alongside Yukina Savoy, senposai and Hakurei turnips. Pam Dawling

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Way back in July 2016, I posted  Insectary Flowers to Attract Beneficial Insects

This post covers insectary flowers outdoors and in, at various times of year. At the end of April we sow several plug flats of different flowers to plant out in Insectary Circles at the ends of our outdoor raised beds.

See my July 2017 Mother Earth News post Insectaries: Grow Flowers to Attract Beneficial Insects In late May or early June, we transplant IPM

flowers in our outdoor Insectary Circles in the vegetable garden to attract pollinators and pest predators. We use circles cut from plastic buckets to surround these clusters of flowers so that inexperienced helpers don’t pull them out as weeds.  We use a combination of sunflowers, dill, borage, cosmos, calendula, tithonia (Mexican sunflowers), zinnias.

Cindy Conner suggested leaving parsley and celery plants to overwinter and flower early.

Hoophouse Winter Schedule Tweaks and Improvements

I’m always on the lookout for ways to pack more crops in, get higher yields, reduce or at least spread the workload. All while nurturing healthy soil and organic food that people enjoy.

Tweaking the Salt Wash-Down Dates

Using a lawn sprinkler to wash down the salt build up in our hoophouse. Photo Pam Dawling

I wrote about Preparing your Hoophouse for Fall and Winter on September 28. I belatedly realized that in my hurry to publish the post I let some out-of-date info slip in. We don’t do our fall salt wash-down in November any more – we prefer early October, while it is still warm enough for the plants to be improved by extra water, rather than drowned and miserable. We have switched from two days in the spring to three, as we think two days wasn’t quite enough water to get all the salt back deep in the soil profile. We had ambitions of doing three days in the fall as well, but I can tell you now, from experience, that we can fit in two days but no more.

I’ve described how we broadfork and rake all the beds in the fall, and the amount I can do in one day (along with all the other tasks) is 1/3 of a 96ft x 4ft (29m x1.2m) bed. That human limitation, and the logistics of crop rotation and planting dates, leaves a small window between preparing the first three beds to get planted (9/6-10/6), and the remaining four (10/10-10/24). It really doesn’t work well to broadfork and rake saturated soil! It’s better to have a few days for the water to soak in. So, we are satisfied with two days of salt wash-down in fall, for the time being.

Catch Crops

Mid-October photo of September-sown tatsoi and August-sown Tokyo bekana. Fast-growing crops make good use of small windows of time.
Photo Pam Dawling

Last fall I noticed that some areas of some of our beds were idle between being prepped and planting dates in November and December.  I hate to waste prime real estate like hoophouse bed space, So this year when we planned our bed layout, we herded all the little late sowings into one bed with the intention of finding some fast-growing crops to put in that space first. We also managed a more rational layout in each bed, planting the various crops in chronological order from the east end to the west.

Next, I researched what we might grow ahead of the main crop. There are some unknowns here. We have numbers of days to maturity for crops in ideal conditions (nice warm spring temperatures), but we are heading into colder temperatures and shorter days. So it might not work out as we hope. However, given our fondness for salad mixes, anything we have to pull up immature will still be eaten and enjoyed!

Salad Mix freshly harvested.
Photo Pam Dawling

The bed in question was all ready to plant on September 30. The areas I could see for catch crops included 11/9 “filler” spinach and filler lettuce, 11/15 tatsoi #2, 12/7 lettuce mix #2, 12/18 mustard salad mix, and 12/20 radish #5.

I decided to put the 16ft (5m) of areas for November 9-15 sowings (39-45 days to go) into 45day Tokyo bekana and the 18ft (5.5m) of areas for sowings after December 7 (79 days available at that point) into 60day Cylindra beets. The Tokyo bekana came up very quickly, and I expect it will be destined for salad greens, which will be very useful as our outdoor lettuce is waning and we’ve just had a patchy frost (early for here) – the colder weather will slow crops down.

Young Cylindra beets.
Photo Wren VIle

The beets have still not come up 9 days later, and the soil is 60F (15.5C). I’ll check again tomorrow. 10 days should be long enough with soil at that temperature. My niggling worry is that the salt wash-down has drowned the seeds. See Root Crops in August. If they are not up at 10 days, I think I will hoe the area and resow with something quicker – perhaps tatsoi (45 days). I was disregarding tatsoi because it will bolt in January. Umm, but this is a catch crop, that we’ll need to pull up in early December – January isn’t even on its calendar!

Carrots out! Cress in!

Belle Isle Upland Cress from Southern Exposure Seed Exchange

Last winter we grew a small patch of carrots because one of the crew really wanted to try them in the hoophouse. I wasn’t a fan because carrots are so slow-growing and provide only one harvest (usually). But I am a fan of democracy and participation, so we grew carrots. We could have harvested them sooner than we did and planted something else (in my opinion), but there they sat all winter.

Oh yes, about that “usually”: you can eat carrot tops and I have used finely chopped carrot leaves as a garnish. A major brand of crackers has carrot tops as one the herbs in their Herb Crackers. Read the small print!

This fall, as we planned our crops, I said I’d prefer not to grow carrots again, but I was out-voted, and hence we sowed carrots. Now those crew members have left, and I gave the evil eye to the carrots. I’d just read an interesting article about nutrient-dense vegetables, and learned that The 5 Most Nutrient-Dense Vegetables Based on Science are watercress, Chinese (Napa) cabbage, Swiss chard, beet greens, and spinach. We’re growing all the others, but no watercress. For the next-best thing, I wanted to try land cress/Upland Cress in our winter hoophouse.  So I hoed off the little carrots and sowed Creasy Greens Upland Cress and Belle Isle Upland Cress from Southern Exposure. They take 50 days to maturity (in spring) and I note:

“The yellow blossoms help nourish ladybugs, syrphids, and other beneficial insects”

So I plan to let some flower in spring for the beneficial insects.

Creasy Greens Upland Cress from Southern Exposure Seed Exchange

Flowers for beneficial insects

September-sown shungiku (chrysanthemum greens) in January.
Photo Pam Dawling

Last year, one of our trials was a collection of annual flowers to attract more pollinators into the hoophouse. None of the ones we tried seemed to do much, except for one shingiku (chrysanthemum greens) which is still flowering! Readers suggested I’d do better to just let some winter brassicas flower instead of growing special flowers. So upland cress might become part of our solution for that! We’re also growing a perennial, yarrow, to attract beneficials.

Shungiku chrysanthemum greens.
Photo Small House Farm

The other hoophouse tweaks on my list are more for spring and summer, so I’ll leave those for another post.