The Yellow Farmhouse Garden

July 31, 2018

High temperatures can damage tomato plants

Last week I saw a lot of gardens having problems with tomato plants not producing fruit. When discussing this problem with gardeners, the first thing I hear from them is usually,” I’m growing lots of leaves but no tomatoes”. Then they go on to attribute it to an overabundance of fertilizer of one sort or another.

Nutrient imbalance may cause problems, but this season it is likely due to the extended hot temperatures we had until the break in the weather happened this week.  Temperatures in the mid-nineties can damage tomato blossom causing them to fall off the plant — no blossoms means no tomatoes. This phenomenon is known as “tomato blossom blast”.

Heat damaged tomato blossoms turn brown.

Heat damaged tomato blossoms turn brown.

There is really nothing we can do to prevent flower damage when the temperatures are so high except wait it out. Now that the weather has moderated, our tomato plants will start producing more blossoms and setting more fruit.

If another heat wave occurs, it’s likely we’ll see another round of tomato flower blast.

Bob

 

November 16, 2017

Three impressive tomato varieties

Filed under: Disease,Vegetables — bob @ 12:12 pm

Earlier in this past growing season I took an informal survey of how a number of tomato varieties were responding to leaf spot diseases. You can go back and read the post to find out how things were going for them at that time.

I kept an eye on them through the season and watched their progress. In one garden I applied a couple of sprays of an organic fungicide, that didn’t seem to make much difference; it may have helped if I kept it up. As expected, on all of the plants, sprayed or not,  the leaf spot symptoms got progressively worse as the fruit on the plants began to grow and develop. It takes a lot of plant energy to produce a crop of tomatoes.

A curious thing happened on one variety at the end of the season. The heirloom variety, Granny Cantrell, began to shake off the fungal infection. While the other tomato plants lost pretty much all of their leaves and most of them actually died back, the Granny Cantrell plants shed their infected leaves and grew very healthy looking replacement leaves. That was something I’ve never seen in a tomato plant. Sure, many varieties struggle to send out more leaves but they never seem to amount to much. Not only were they growing leaves but they were also ripening existing fruit and producing new tomatoes to boot! Our growing season is too short for the plants to continue to grow so I’ll never know if the new shoots would have continued to grow without leaf spot symptoms. It may be a useful trait that tomato breeders could use to develop a new variety.

Notice the new green foliage on the Granny Cantrell plant on the right compared to the defoliated tomato on the left.

Notice the new green foliage on the Granny Cantrell plant on the right compared to the defoliated tomato on the left.

Juliet was another noteworthy tomato. They had good resistance to the diseases throughout the growing season and produced a huge crop of tomatoes, far out pacing any variety I grew this year.

All of the tomatoes I grew were tasty, how could they not be? since they were vine-ripened and eaten right after picking. All the people who tasted the tomatoes; and there were quite a few, agreed that Cherokee Purple was their hands down favorite. Cherokee Purple however,  had little disease resistance and didn’t produce very many tomatoes at all. They also have very thin skin making the very hard to handle without damaging them. They are not a typical red tomato so their coloring made it harder to distinguish when they were ripe. Also their flesh inside has a distinctive purple hue that, along with their taste makes the quite memorable.

Bob

 

 

July 19, 2017

Tomato disease scores

This is the time of the season when tomato plants start showing signs of disease infections, usually as different shapes and colors of spots depending on which particular disease has infected the plant.

Last week I took an informal survey of several varieties of tomatoes to see how each variety is holding up under early disease pressure. My MO was to look for leaf spots on the plants. I made no attempt to identify which disease was causing  what spots. Then I ranked them on a scale of zero to ten depending how bad the plants looked. Zero meaning no spots were visible, ten meaning severe symptoms. No plants were bad enough to score what I imagined to be ten.

I didn’t count how many leaves were infected; or measure how many square centimeters were discolored; or brix levels of leaves; or levels of ethylene gas; or any other scientific criteria. Heck, I didn’t even alphabetize the list of varieties. I ignored any cultural differences such as mulch, staked or caged plants, planting history, etc. .Over half were heirloom varieties, some of those looked quite good compared to the modern ones.

I surveyed about fifteen gardens in two different locations about 20 miles apart. I made a point to look at them all the same day because twenty four or even twelve hours could mean the difference between no spots and spots. Here’s a chart of what I came up with:

Tomato variety Plant score
Brandywine 3-6
Belarus 0-1
Cherokee 1
Juliet 0-1
Sheboygan 0
Pruden’s Purple 0
Granny Crantrell 1-2
Super Sweet 3
Belstar 3
Pink Honey Drip 3
Roma 4-6
Yellow Cherry 5
Large Red Cherry 6
Early Girl 3-5
Rainbow Blend 3
Roma Type 7
Beefsteak type 6-7
Brandywine Pink 6
Moon Glow 3-4
San Marzano 3
Bobby’s Girl 0
Chadwick Cherry 0-1
Unknown varieties 5-6

Pruden’s Purple, by far looked the best it has no spots and  very vigorous leaves. Chadwick Cherry came in a close second. There were a few different beefsteak-type tomatoes that were not specifically tagged by variety but all of them had more advanced disease progression.

Keep in mind this is only a snapshot of conditions for one day. That could all change later on as the plants begin to get stressed by fruit production.

Bob

 

 

August 25, 2016

Powdery mildew on pumpkins

Filed under: Disease,Pesticides,Vegetables — bob @ 7:36 am

Growing pumpkins and squash has changed sine the early days early days of my career. Back then, pumpkins rarely had any problems whatsoever. You could just plant some seeds, keep the patch weeded and you were pretty much guaranteed a fine crop.

This year demonstrates how times have changed. In addition to the squash vine borer and squash bug that I talked about the last couple of weeks, we are now seeing powdery mildew on our pumpkins and squash.

Powdery mildew shows up as a white powdery-looking coating on the surface of the leaves. It eventually cause the leaves to turn yellow and die. Under certain conditions it will eventually kill the entire plant.

We’ve had textbook weather conditions for the development of powdery mildew. This type of mildew is a fungus that thrives when daytime temperatures are high and nighttime temperatures are low enough to form morning dew.

Some varieties of pumpkins and squash are more resistant to powdery mildew than others. Here are two different varieties growing side by side.

Some varieties of pumpkins and squash are more resistant to powdery mildew than others. Here are two different varieties growing side by side.

Unlike most other fungi, powdery mildew does not need liquid water to infect a plant and grow. High humidity within the leaf canopy provides the environment powdery mildew requires.

We do not see much powdery mildew during rainy years. As a matter of fact, one non-chemical approach to controlling powdery mildew takes advantage of this. Spraying the surface of the leaves with overhead irrigation will wash off much of the infection. It also will cause existing spores to absorb so much water that they burst, greatly reducing the source of new infection. This method only works if the area is well drained, otherwise you will end up causing other problems due to excess water.

Commercial chemical and organic formulas are available on the market to control this disease. I’ve been using a homemade concoction that has been working pretty well for me. I mix one table spoon of baking soda and two tablespoons of Murphy’s Oil Soap to a gallon of water. Spray it onto the leaves no more than every seven to ten days. It’s important to use this ratio, a stronger solution will damage leaves.

The spores from the species of powdery mildew that infects the squash family of plants does not survive Michigan winters. Spores are blown in to Michigan on southerly winds each spring to start a new cycle of disease.

Powdery mildew is very species specific, meaning each species of plant is infected a specific strain of fungus. For example, the powdery mildew that infects lilacs cannot spread over to squash and vice-versa.

This, I hope, will be the last problem we’ll have to deal with on our vine crops this year.

Bob

 

 

April 28, 2016

Chamomile tea helps protect young seedlings

Filed under: Disease,Seed Starting — bob @ 7:11 am

In my last post we discussed damping off, a fungal disease that attacks and kills developing seedlings. A clean growing medium will minimize the occurrence of damping off.  And a seed starting mix can be pasteurized by pouring boiling-hot water through it.

Once the seeds have germinated and the newly emerged plants are off to a good start, there’s more you can do to protect those tender seedlings.

There’s plausible evidence showing some homemade concoctions can inhibit the growth of pythium, the fungus responsible for damping off. One of these is chamomile tea. That’s right, the same tea we brew when we feel like mellowing out with something warm to drink.

Steep at least two teaspoons of chamomile flowers into each cup of boiled water. Let the tea come to room temperature before straining and using. This is quite a bit stronger than what most people use to brew a cup of drinking tea. The stronger you make the tea the effective it is.

 

Chamomile grows wild in some gardens.

Chamomile grows wild in some gardens. Every year we collect chamomile for tea. 

Use a spray bottle to water your new seedlings by spritzing the tea over the plants and soil once a day. To help the tea be more effective, make sure you allow for plenty of air movement around your plants while they are growing.

Eventually Mother Nature will take over and you won’t need to use the tea anymore. As seedlings grow and get older they will outgrow their susceptibility to damping off.

Bob

 

 

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