Sunday 13 July 2014

Hey Folks:

Instead of a post this week, I am creating a new activity for the Curious Food Page.  It should be up in a few minutes, and updated somewhat over the course of the summer.

The old curious food page has been pasted below, for those of you who are taking part in the "grow your own potatoes" project.


Grow Your Own Seed Potatoes

Hey Folks:

I may have a few extra seed potatoes this spring. If I do (I should know by late May), you may wish to consider the following project. Especially good for those of you who have children who are interested in growing some relatively easy crops. Some of our interns did this last year at their homes.  This offer is open only to subscription customers and interns. First request, first serve.


What you need:

One planter per seed potato. 10-12 inch diameter, 10-12 inch depth (or more). Needs a couple of drainage holes. Planters could be any receptacle (ceramic, wood, or plastic pot planter, bucket, or anything else that drains…apparently they can also be grown in plastic bags though I have no experience with this). If your planters are smaller than 12”, then the tubers will be smaller.

Sunny location (south facing porch is ideal).

Potting Soil. This may take a bit of care to source. Ideally you want a potting soil that is

-Certified Organic (There will be a certification stamp that specifically says “certified organic” or “certife biologique”). Your next best choice is a potting soil that is “natural”, though what the producer/manufacturer claims is natural is anyone’s guess…

-The packaging should indicate that it is compost enriched. If you cannot find enriched soil, I can bring a few scoops of compost to you. If you have access to your own compost, it should be well rotted, without anything recognizable in it – it will look similar to soil.

If you are really pressed for potting soil, or only need enough to fill a planter or two, I may be able to work something out with you.

Preparation:

Clean your planters with a mild soap solution, and rinse them well.

Fill the planters ¾ full with soil. If you are adding compost, mix it well with the soil to disperse it evenly. You need to leave about 4 inches between the soil surface and the rim of the planter. Set aside enough potting soil to add a couple more inches later.

Sowing:

Scoop out a hole large enough for the seed potato, and push the potato in so that it may be covered by about 2-3 inches of soil. Cover it over, and press the soil gently around it to ensure there are no air pockets. Giving some water at this time should help remove air pockets as well.

Watering:

Keep the soil moist but not soaking. If it dries out a little, that is ok. Watering too much might stress the plant. If the soil appears dry, press your finger into the soil. There may be enough moisture just below the surface.

If your planter has a drain basin, fill this with water and let the moisture wick up through the soil. Otherwise, water the soil around the edges of the planter, so that the potato remains covered. If watering exposes the potato, simply cover it over.

Growing:

The plant should emerge in about 2-3 weeks. Continue to water periodically. Three to four weeks after the plant emerges, top up the soil another two inches. The tubers need to remain covered so that they do not “green”.

Harvesting:

Potatoes should be ready for harvest about two months after planting. The leaves and stems will begin to die back. This is the sign that the tubers are ready.

Pull the entire plant out (You will need a place where spilling a bit of soil is ok). Make sure that all the tubers came out with the plant – check the soil in the bucket for more.

You can expect between two and four pounds of potato per plant.

Things to remember:

If you use tobacco products, be sure to clean your hands before handling the seed, planter, plant, watering can, or soil. Tobacco mosaic virus can infect the potato plant.

If the leaves yellow a little bit, you are either providing too much or too little water.

White flies. Mix a 40:1 solution of water and mild dish detergent and spray the leaves. Spray underside of leaves as well. Repeat two or three times over the course of a week.

The Colorado Potato Beetle is a yellow and black striped beetle. The larvae are red and black. Pick and squash both of these. You may find their yellow eggs on the underside of the leaves, these you can wipe off with your thumb.

I will know by late May if I have extra seed potatoes. Let me know in advance if you are interested.

This offer is open only to subscription customers and interns. First request, first serve.


Colorado Potato Beatlemania

One of our customers wanted to know how I managed the Colorado Potato Beatle.

First, I want to emphasize an important point about “pest” management at Whitsend.  I prefer to maintain a plant positive approach as opposed to a pest negative approach. 

Healthy crops will have more resistance to insects than unhealthy ones.  Plant immune systems deploy an array of phytochemicals that help ward off or slow the progress of bugs.  

Plants not yet infected detect these chemicals, which then stimulates the immune system of unaffected plants.  As well, there has been recent research indicating that plants “communicate” insect attacks to each other via mycelium networks between each other’s roots.  (I looked for the article on BBC Nature, but cannot find the link – Ed.)

This Beatle and the European Leek Moth are the insects that have the most potential to reduce crop yield at Whitsend.  They are also the most time consuming to manage.  My goals for insect management are: to reduce the amount of time I spend managing insects, to reduce the number of stresses on the plant so it is more resistant, to reduce the spread of the insect during the growing season, and to reduce the population that winters over.  Managing the Colorado Potato Beatle requires a multi-faceted approach.

Potato variety:  This season, I have five varieties of Potato - the early Onaway and Red Norland varieties, mid-season Dakota Pearl, and late-season Red Chieftain and Agrea potatoes.  I kept at least one bed of each variety near each other to monitor how the different varietie react to different bed preparation methods, soil amendments and stresses such as the Colorado beatle.

The early potatoes definitely had the highest Potato Beatle populations.  This may have been due to the life cycle of the beatle, whose initial population peak coincides with the start of the potato season.  However, I observed that the Dakota Pearl and Red Chieftain had minimal beatle damage, despite being located next to the most affected plants.

Row Covers:  I have used row covers to keep beatles off the crop.  The row covers  are placed on the bed when the potatoes are planted, and held in place with smooth stones (some growers prefer to bury the edges of the covers with loose soil, but I think this makes uncovering the beds too time consuming).  I have had mixed results using row covers.  They seem to be most effective during the early stages of potato plant growth than later.  As well, row covers reduce sunlight by about 15% (or more if they are not kept clean).  This stresses the plant and forces it to put more effort into leaf growth (less growth for the tubers).

I usually leave one plant uncovered, for two reasons.  First, the “canary” lets me know when the beatles have arrived for the season – they take up residence on the most available plant.  Second, I know that the plant responds to these first beatles with its phytochemicals, which in turn are detected by the other plants. 

Inevitably, some beatles manage to get under the covers.  In some instances, the beatle population remains low and a “pick and squash” sweep of the beds keeps the insect population down.  However, this is quite time consuming, and sometimes I cannot check a bed for several days.  Sometimes a bed that is beatle free during one check has infested plants during the next check.

This growing season, I removed the row covers on the beds that the beatles had managed to establish themselves.  Without the covers in the way, it was less time consuming to do the pick and squash sweeps.  Within days, I observed an increase in the numbers of Assassin Beatles, Shield Bugs, Ladybirds and Spiders.  Counting was not necessary, as the change was surprisingly dramatic.  I even saw my first Praying Mantis on the farm here.  As the predator population always follows the prey population, it seems to me that having the covers on will delay the predators getting into the beds in time to provide their own control of the beatles.

On a hunch, I started taking the covers off after the plants were established, leaving them exposed.  (These were the Dakota Pearls and Red Chieftains immediately next to the infested Red Norland).  These beds hosted a small population of beatles that was easy enough to manage with pick and squash sweeps.  However, I observed that the egg, larvae and adult populations on both varieties did not rebound at the same rate – the beatles on the Norland and Onaway potatoes seemed to rebound quickly, whereas the beatles on the Cheiftain and Dakota Pearl potatoes levelled off and then declined.  By the time I was harvesting the Norlands, the Dakota Pearls were virtually beatle free.

Seasonal Timing:  I planted my second round of Chieftains and the first Agrea potatoes without using the row covers.  These plants were about 20 feet away from the last succession of the Dakota Pearls, but I detected no beatles, larvae or eggs.  This was mid July when these plants became established.  I suspect that the beatle population was reaching its inevitable “trough” at this time.  Last year, we had one additional “peak” in population toward the end of summer.  I am currently looking into the seasonal life cycle of the beatle to see if, by timing my plantings strategically, I can avoid the period of summer when the beatles are most numerous.  

Looking back on my first year (when I saw only one beatle all year) my records indicate that my first planting was in mid June, with the potatoes emerging ten to fourteen days after (i.e. late June early July).  So timing can be a factor in the relationship between the beatle and the crop.

Crop Separation:  This was an unintentional find.  Due to space limitations, one of my first two plantings of Dakota Pearl wound up being at the opposite end of the growing field.  Despite having its row cover blown off by wind on a couple of occasions, it remained beatle free from sowing to harvest.  Having established themselves in an area where the potatoes were most concentrated, the beatles had no reason to travel to the more distant bed.

Straw mulch:  Some have reported success (including Elliot Coleman, “The New Organic Grower”) by using a thick mulch of straw around the base of the plant.  Add the mulch as the plant grows, keeping just the foliage crown uncovered.  I think this interferes with the beatle’s life cycle, as it progresses from its larval stage on the plant to its pupal stage underground, and then back to its adult stage back on the plant.  This technique is not suitable for us, as the straw mulch became a haven for mice, which destroyed a considerable amount of my potato yield last year.

Insecticides:  The Colorado Potato Beatle feeds off plants in the Nightshade Family.  These plants contain a wide array of glycoalkaloids, which are potentially toxic.  The beatles have evolved an internal chemistry that resists toxins.  In fifty years of using or experimenting with insecticides as a means of control, the Colorado Potato Beatle has been able to develop a resistance to fifty-two insecticides.  Resistance to DDT was reported as early as the early fifties.  Some populations had evolved this resistance within a single year.

Using so called “Organic Pesticides”, such as Pyrethins, has had similar results (note that no pesticides discriminate between a potato beatle and an assassin bug or mantis). 

Besides, this is a pest negative approach.  An hour of time spent fighting beatles means one less hour in which the plant itself can be tended (the plant positive approach).  One hour of tending the crop not only reduces the effect of the beatles; it also improves plant health and ultimately, its total food yield – which is the point of growing crops in the first place.

Summary:  The way you manage your potato beatle population will be determined primarily by your unique growing situation. 

Keep records of your potato crop, including its yield, its place in your crop rotation system, and which methods you use from one year to the next to protect them from infestations.  This knowledge will allow you to develop your best strategy for growing a healthy crop with the least amount of effort.
Consider using less machinery.  Frequent surface cultivating with an ergonomic co-linear hoe is more effective for your plant health, weed control, water retention, and top-dress incorporation than a once-per-season machine tilling.  I also find it more meditative,  gentler on the arms, and a good way to "warm-down" at the end of a long day of more strenuous tasks.  A healthy farmer makes for a more healthy farm.  You tend to see more of your soil and plants when you are focused on a small hoe than when trying to manoeuvre  a large piece of machinery.

Most importantly, look at your growing area as a whole unit.  There may be stresses on the plant, such as poor drainage or low water holding capacity in the soil, low quality compost or an imbalance between various macro and micro nutrients.   There may be nightshades that harbor beatles (or their eggs) in the spring, before the potato crops have emerged. 

You may also find that your field includes beneficial insects, birds, frogs, toads, shrews, skunks, and other insect and larvae predators.  Look for ways to encourage them. 

Recall earlier that I mentioned finding my first Mantis on the farm among plants that had beetles on them.  Since then, I have seen two more Praying Mantids at different stages of growth (therefore, could not have been the same individual).  Knowing that Mantids will consume a wide variety of insects, I could argue that my Colorado Potato Beatle population is not a pest.  The beatles, too are food for your garden inhabitants and for your farm.

Always use the plant positive approach – you are a plant grower, not a pest controller.



Sources:  BBC Nature, various university extension service websites, and CFIA and OMAFRA info pages.  I have also drawn on my own crop records, conversations with Henry Ellenberger of Ellenberger Organic Farm, and my internship at Elm Tree Biodynamic Farm.