How's that for an uplifting blog title! It's not as bad as it sounds! I wanted to spend a little time today writing about some of the diseases we battle in our vegetable fields and how we manage them using organic approved methods.
Just like human health, plant health is best achieved by preventative measures and a healthy growing environment. In organic agriculture, treatment of disease after it occurs is often nearly impossible. Therefore, we focus on prevention. The preventative measures that we take to reduce the risk of disease include: avoiding overhead watering of vulnerable crops unless absolutely necessary, choosing resistant varieties, providing adequate ventilation around plants, keeping tools and equipment clean, avoid working in plants when the foliage is wet, ventilating the caterpillar tunnels, and planting in biodegradable mulch to prevent soil splash back. The majority of the common diseases we see are fungal or bacteria based organisms that proliferate in moist and warm (but not hot) environments. These diseases can include downy mildew, powdery mildew, early and late blight, and cercospora leaf spot.
Also like human health, the nutrient density of the plant's food affects the health and immunity of the plant. Plants receive their nutrients through the soil, so if the soil is depleted, the plants will be more susceptible to diseases and pests.
Despite taking these measures, farmers will almost always see some disease in their fields each year. The severity of the disease is affected most by weather conditions and the speed at which we identify and destroy the diseased plants.
There are organic approved sprays that can help to reduce fungal and bacterial infections, namely Sulfur and Copper. We have chosen not to use these sprays on our farm for several reasons. Of the two, sulfur is less damaging but it is a broad spectrum treatment, which means that along with killing undesirable pests and disease organisms, it also kills beneficial insects and organisms. Since our honeybees, as well as bumblebees and other pollinators, are always at work in our crops, we would risk killing them when spraying. Copper is also broad spectrum in nature and bio-accumulates in the soil which can cause toxicity to plants and animals grown in the area in the future. On top of this, both substances require the farmer to wear a respirator to avoid inhaling as they will damage the lungs.
The substances we do use to prevent or treat disease are hydrogen peroxide, baking soda, hot peppers and garlic, and soap. These are much more innocuous although not without issues. Some beneficial insects can be killed or harmed by these substances.
You are probably wondering what diseases we have seen in our fields this year! The two primary diseases we are seeing are Late Blight in the tomatoes and Downy Mildew in the cucumbers. So far, we have slowed the progression of late blight in tomatoes by pulling all plants that were showing early signs of the disease. This meant that we pulled all our field tomatoes (about 200+ plants). The tomatoes in the caterpillar tunnels are just now showing some minor signs of the disease, but we won't be pulling these. Since they are in the midst of ripening we are going to leave them and play the ripening vs. disease progression game. Share members from last year will remember that we lost all our tomatoes to late blight which was very disappointing. Late Blight is every tomato (and potato) grower's worst nightmare because it can move so quickly and be highly destructive. That said, the symptoms are currently contained to the leaves and the fruits look good. I predict that we will have a few weeks of tomatoes but not an extended season.
There is much research currently being done by the University of Guelph and others to determine why Late Blight has become so widespread and problematic since 2009. We had a plant pathologist visit our farm and test our tomatoes to see which strain we have in order to help them determine how the strains are moving and reproducing. The short version hypothesis is that the 26 existing blight strains are cross-reproducing and creating 'super pathogens' that are resistant to our current methods of control. For some historical context, it was Late Blight that caused the Irish Potato Famine in the mid-1800's.
As for the Downy Mildew in our cucumbers, we ended up pulling all the plants to prevent spread to our winter squash and summer squash. This means cucumbers are at an end, but the plants were so damaged they were no longer producing properly anyways.
As farmers, it's always very frustrating to lose an entire crop. Luckily, the CSA model means that we have many different varieties and types of vegetables planted which lessens the economic blow. Diversity is an essential part of a viable and vibrant farm, in my opinion. While I hate to jinx things, we have many crops that are looking beautiful and un-bothered by diseases or pests. Peppers, root crops (carrots, beets, parsnips), all the brassicas (cabbage, kale, broccoli, etc.), and lettuce are doing great!
In other news, we rose bright and early Saturday morning to pull the poly on our greenhouse. This will become our heated greenhouse where seedlings are started in the winter. The plastic must be pulled in the early morning because any wind makes the job impossible.
Weekly Share Contents:
Head Lettuce or Spinach
Cabbage or Fennel
We may see some tomatoes this week as well....they are starting to ripen nicely.
A favourite around here, beets are sweet, nutritious and versatile. While roasted is a classic way to prepare beets, with the summer heat it can be nice to use beets raw instead. Check out this link for some great beet recipe ideas : http://www.foodnetwork.ca/in-season/photos/25-beautiful-recipes-you-cant-beet/#!ac22f66dbe049ba812d041e504b06927