Growing flowers to attract aphid predators in early spring

Last July, when sheltering indoors from the heat, planning next winter and spring’s hoophouse crops, I researched and wrote up Controlling Aphids in Early Spring

I also have a post (another July information-gathering project!) about Insectary Flowers to Attract Beneficial Insects 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. We hope to find a similar approach that will work earlier in the year for hoophouse and greenhouse aphids.

Aphid predatory insects such as ladybugs, lacewings, aphid  parasites, damsel bugs, braconid wasps, rove beetles, syrphid flies, and spined soldier beetles are attracted to plants with small flat open flowers, like alyssum, dill, yarrow, buckwheat, sunflowers, and cosmos. This is a rather loose and general statement. 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. Organic Integrated Pest Management from ATTRA gives wider information about managing pests organically.

 

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.

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. We 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. We are implementing our plan that we made in the summer.

Insectary flowers against aphids

Meanwhile in January we got bad aphids on the lettuce and, of our flowers 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.

There are many kinds of aphids. The lifecycle of aphids starts 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.

This week, I want to give a progress report on the flowers we are growing. The chart gives details of the ones we chose, where we found the seed, and which months we decided to plant them in.

The first planting, in September, was of borage and shungiku (Chrysanthemum greens) only. We hoped these would give us early flowers to start the program. Those plants became big enough to transplant in the ground and in 8” (20 cm) pots. We thought having some in large pots would enable us to move them to the trouble spots.

What I have noticed is that plants in pots dry out very quickly in both the hoophouse and greenhouse! The shungiku have looked close to flowering several times, and the accidentally dry conditions should have helped them to panic and bloom, but they haven’t. The borage flowered with pompom-like clusters, much more compact than spring outdoor borage does.

The second planting, in late October, consisted of Meadowfoam, Tidy Tips, Phacelia and Yarrow. Those plants are still small, as I write this at the beginning of February.

They have been potted up from cells to 4” (10 cm) pots, and some are ready for bigger pots. No flowers, no help against January lettuce aphids.

The third sowing has just happened, on February 1, and includes borage, shungiku, Meadowfoam, Phacelia, Tidy Tips and yarrow. I forgot to sow alyssum, so that will be a little later.

The September-sown borage and shungiku both had some troubles with cold temperatures during January. We had a mild December, then a January with three non-consecutive nights at 10F (-12C). In our double-poly hoophouse, we roll out rowcover at night if it threatens to be 8F (-13C) or lower outdoors. That was about 6 times so far, but 10F (-12C) has been our coldest. Some of each of the borage and shungiku got cold-damaged, and some got rowcover-damaged (hasty pulling!)

So far, no beneficials have been seen on the borage flowers, and no aphids have been killed as a result. We’re still hopeful, especially about reducing aphid numbers on the peppers. More progress reports to come!