Review: Preventing and Treating Flea Beetles and Aphids on Canola and Sugar Beets with Nutrition Management

This is my review of a publicly available recording of a webinar (without the images), available on the Kind harvest website, with hosting and presentation from John Kempf and presentation from Tom Dykstra.

So easy, yet maybe so hard.

HEALTHY PLANTS

The punch line from this presentation is that healthy plants will naturally defend themselves from insects (and diseases). What is defined as a healthy plant is probably the first step into the thinking of these presenters. Here, a healthy plant is not just one that is green, currently free from disease and pests, and is producing whatever it is we want it to produce. A healthy plant is one that, through access to the right nutrients, is able to synthesis proteins to full capacity and as a result also has high leaf sugars.

PROTEIN SYNTHESIS

John focuses on this. His point is that having the right nutrients at the right time, plants will synthesis proteins successfully. The basics of this are: no nitrate N at sowing as this is the number one way of upsetting the balance of this process, good access to Mg, S, Mo and B for protein synthesis, and good access to Mg, Mn, Fe and P for photosynthesis. Good genetics are also important.

HIGH LEAF SUGARS

Tom focused on brix from leaves and how high leaf-brix = no insects. When he laid out this, it seems so easy, but he also notes that the road to low-leaf-brix-hell has been a long one and that turning it around will also a long one. The story he gave is that sugars are deadly to insects and once upon a time, all plants were high leaf-brix, so only the truly sick plants were eaten by insects. There is an order to the types of insects that attack the plants, based on this leaf-brix. The numbers he gave were:

• leaf-brix >14: no insect damage
• leaf-brix 12-14: basically only larger insects like grasshoppers
• leaf-brix 9 -12: chewing insects
• leaf-brix <9: suckers
• leaf-brix 6-8: aphids

Tom states that at leaf-brix 9, aphids will actually die, and quickly, from sugar overdoses. Crystallisation? Caramelisation? I can’t remember the word he used, but it sounded tasty.

For the flea beetles, they general do the most damage to cotyledons and the first leaves, which means that the plant need to get these leaf-brix forming nutrients from its seed.

IMPLEMENTATION

I think this is the second step in adopting the approach discussed in this webinar. Implementation isn’t about a target level of nutrition for a maximised harvest, but a target level nutrition for a balanced level of synthesis activity in the plant. Additives are not discouraged at all, but precision (temporally) is really important. Again, no nitrate N at sowing was encouraged, targeting the 7 nutrients that usually are deficient in unbalanced protein synthesis plants (Mg, Mn, S, Mo, B, Fe, P), and even seed treatments were all put forward. Above all, breeding for this type of plant health was seen as the best long-term solution.

RESEARCH QUESTIONS

To begin with, we need to convince everyone (including me) this way forward is possible. John is adamant that it is, but seeing is believing. I think we’d have to start with some observations in our current trials: are there varieties that maybe do have the Kempf definition of plant health still in their genetics and seem to be more immune to diseases and pests? Do we see less aphid issues in the sites where the 7 nutrients are sufficient? Do we see lots of aphids on the high N trial plots we occasionally run? Do we see less aphids in varieties that have problems with “higher leaf-brix” insects – maybe gammafly? What are the leaf-brix numbers we are seeing?

In all, I don’t really see this approach as too controversial. We generally worry about nutrient deficiencies already, and we know that the temporal precision of nutrients matters. We are certainly worried about jordloppor and aphids.

John put out the offer to partner as an advisor with farmers who were willing to commit to following this approach. Maybe we should see if he’ll partner with research organisations?