The Yellow Farmhouse Garden

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.




July 12, 2017

Rose sawfly emergence

If you ever grew roses you probably have seen those ugly, slug-like rose sawfly larvae eating leaves on your roses, or at least the damage they do. That’s the way we usually see them, as larvae. Rarely are the adult insects ever seen by gardeners.

Rose slugs feed on one side or the other of the leaves, usually it’s the underside. When they first hatch from the eggs and while they’re growing, the slugs are very small so they have very small mouth parts. That means they can’t take very big bites and only able to eat the softer leaf parts leaving the tough veins of the leaf.  And they only eat one surface of a leaf leaving the other side intact. This results in a characteristic “windowpane” feeding pattern. Later as the leaf parts dry, the windowpanes turn brown and fall out. It’s not unusual for an entire rose bush to be defoliated like this.

Last week, on some ‘Knock Out’ roses, I witnessed a surprising phenomenon, a swarm of rose sawfly adults. It was a frenzy of activity, hundreds of them flying in and out the the rose branches stopping only briefly to mate. They would swam all over one bush then move on to the next until they visited all nine rose bushes. The way they were flying really looked a swarm of bees or wasps. That should not be too surprising since they are are members of the insect order Hymenoptera which includes bees, ants and wasps among others.

Unfortunately, I wasn’t able to capture a video for you but I got a few photos.

The adult sawflies do not chew on buds.

The adult sawflies do not chew on buds.



Sawflies were on every part of the plant.

Sawflies were on every part of the plant.

Closeup of adult sawfly.Closeup of adult sawfly.

The entire event lasted about two hours, then they were gone, with just a few stragglers left behind. I assume they laid eggs on the rose plants during all that activity. I’m expecting a huge outbreak of rose slug larvae from them.

When all that was going on, I was thinking that I had two choices: I could spray all of those sawfly adults as they were buzzing around and destroy them right then and there; or just leave them alone to see what eventually happens. Actually, since I didn’t have any insecticide or sprayer at the time, the decision was already made.

This will be an unintended but interesting experiment. I’ll let you know how it turns out.










July 11, 2017

Cucumber seeds fail to come up

Filed under: Insects,Vegetables — bob @ 8:17 am

A couple of gardeners I know asked me why their cucumbers didn’t come up this year. Others have mentioned that their beans didn’t come up either. Was there something wrong with the seeds this year?

After inspecting a few gardens, it became apparent to me what was going on. In each case, there was a heavy infestation of striped cucumber beetles. They are voracious feeders and are always on the lookout for their preferred food, cucumber vines and related plants such as melons and other vine crops.

In those gardens, the beetles ate every plant they could find that tasted like a cucumber. The sprouts just emerging from the soil were particularly vulnerable which is why it appeared that the cucumbers didn’t come up — they ate every last bit of the tiny cucumber sprouts before the gardener knew what happened. And larger, young transplanted cucumber plants were well on their way of disappearing down the gullets of the beetles. When the vine crops were all gone, they moved over to the bean sprouts and ate those down to the ground. Even older bean plants had lots of holes in their leaves from the beetles.

Striped cucumber beetle.

Striped cucumber beetle.

Striped cucumber beetles are about a quarter of an inch long. They have bright yellow bodies with distinct black stripes running the length of their wings.

This was just the first wave of cucumber beetles, we can expect one or two more generations of beetles to show up later this season.  This generation of beetles will lay its eggs at the base of the plants in the garden. Later they will hatch, feed on plant roots for a while then pupate and emerge as adults later in the season. The next generation of beetles will feed on the underside of the leaves and even chew gouges in the fruits.

Even more important, cucumber beetles carry and will spread bacterial wilt, a serious disease of vine crops. Infected plants wilt and never recover. There is no cure for bacterial wilt once it infects a plant. It’s very disheartening to see your cucumber vines grow and begin to flower only to lose them to wilt. So it’s a good idea take care of cucumber beetles as soon as you find them. Hand picking doesn’t work because they can get away too fast. Instead, apply an insecticide labeled for cucumber beetles, most garden insecticides are effective against them.




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