Good Garden Practices Prevents Problems

Good Garden Practices

Tom Ingram: Ask a Master Gardener

Tuesday, June 23, 2020 

Q: It seems like there is always something wrong in my garden. If it’s not insects, it’s some sort of disease. What am I doing wrong? JK

A: It can seem like that sometimes but let us talk a little bit about disease prevention rather than just how to deal with disease once it happens.

Resistant plants and seeds:

If you start your vegetables from seeds, purchase disease-resistant seeds. If you are like most people, you will say, “How the heck do I do that?” Well, most vegetables have varieties that are more disease resistant than others. Heirlooms (for example) are typically traditional cultivars that have been passed down from generation to generation that remain true to their heritage. As such, they can be more susceptible to disease because they do not have the advantage of having disease resistance bred into them via hybridization. Hybrids are not GMOs; they are varieties that have been cross-pollinated with other varieties to either increase production, increase disease resistance or both. For example, seed packets for tomatoes indicate their disease resistance with the letters V, F and N. Seeds with those disease-resistance indicators would be naturally resistant to Verticillium Wilt, Fusarium Wilt and Nematodes. So right from the start, you are ahead.

Also, try to purchase healthy plants. As gardeners, we all know that the bargain table with the sickly looking plants can be tempting. But try to remember these plants are there for a reason. The reason might be disease. If you cannot resist (and many of us can’t), try to keep them away from your other plants until you nurse them back to health.

Crop rotation

If you plant tomatoes in the same spot every year, disease pathogens can build up in the soil, becoming a bigger problem each year. To counteract this, you can rotate your crops. Some people rotate every year, but for sure, it’s good practice to rotate at least every three years. But here is the trick; you need to learn about the vegetable families because vegetables in the same family are usually susceptible to the same diseases and you might be surprised by who is in the same vegetable family. Tomatoes are in the solanaceous family, so are potatoes, eggplant and peppers. So if you are going to rotate your crops, don’t plant potatoes where the tomatoes were. Brassicas include broccoli, cauliflower, Brussels sprouts, kale, radishes, etc. Legumes include the bean family. And the others kind of make sense. So rotate by family, not just vegetable.

Garden practices:  You need to be aware of how your garden practices might be contributing to plant disease. First, you should water in the morning. When you water in the morning, the water can evaporate off the plant and soak into the soil before the heat of the day. Watering at night can leave the leaves of your plants wet, and wet leaves are more prone to disease. Also, be sure to water the roots, not the leaves. The roots need the water, the leaves do not.

And clean your tools. If you have been trimming or pruning infected branches or leaves, wash your tools with a 10% bleach solution to prevent spreading the disease to other plants.

If these habits become part of your garden practices, you will be well on your way to minimizing plant disease and being a happier gardener.

Garden tips

·        White grubs will soon emerge as adult June Beetles. Watch for high populations that can indicate potential damage from grubs of future life cycle stages later in the summer.

·        Fertilize warm-season grasses at 1 pound Nitrogen per 1,000 square feet. Do not fertilize fescue and other cool-season grasses during the summer. Because nitrogen is soluble in water, much of it may have been lost due to percolation and runoff if you fertilized before recent rains.

Squash Vine Borers

Brian Jervis: Ask a Master Gardener

Sunday, June 21, 2020

Q: My squash plant was big and beautiful, and then one day, the leaves started turning yellow and in a few more days it was dead. What happened? RW

A: The culprit was likely the squash vine borer. These insects can be a problem for all cucurbit plants and are the reason many of us no longer grow squash but grow cucumbers instead. Yes, I know cucumbers are cucurbits too, but they don’t seem to bother cucumbers like they do the squash.

Squash vine borers overwinter in the soil as either larvae or pupae. Adult moths begin to emerge in June (possibly sooner if we have a mild winter like we have had) and remain active through August.

During this time, they find a mate. The female deposits her eggs, usually about a dozen or so at a time, on the stem of the squash plant near ground level. The eggs hatch and the larvae enter the stem to begin feasting on your beautiful squash plant. They essentially eat out the inside of the stem, destroying the plant’s ability to draw up nutrients into the rest of the plant.

Signs of this not only include the yellowing and wilting of the leaves on your squash plant, but you will also see something that looks like wet sawdust on the stem of the plant. This is the excrement (frass) of the borer inside of the stem.

These larvae continue to feed for four to six weeks and can migrate to other plants if their host plant dies or ceases to become suitable for their needs.

These borer larvae are white or cream colored and can be easily seen by slicing open the vine in the affected area. The fully grown moth is primarily black and orange and is easily mistaken for a wasp.

Squash vine borers are worthy adversaries and controlling them can prove difficult. The first line of defense will require diligence on your part. This entails visually inspecting your plant stems near the soil line for eggs. If eggs are found, they can be destroyed.

If you missed the eggs and are seeing evidence of the squash vine borer (frass), you can gently slit the stem and remove the larvae. Once removed, you should cover the damaged part of the stem with soil. With any luck, you will continue to get production from your plant.

Weekly preventative applications of an organic insecticide during the active months can also help. An organic pesticide like spinosad should be applied to the stalk of the plant near the soil level during their period of activity. But be careful to only spray the base of the stalk and spray late in the evening, as you don’t want to harm any of the pollinators working on your behalf to get you some squash.

As an alternative strategy to weekly pesticide spraying, pheromone traps can be placed in your garden near your squash plants. When the squash vine borer moth shows up on your trap, you know it is time to begin spraying the stalks near the soil with spinosad.

And last but not least, because squash vine borers overwinter in the soil, tilling the soil at the end of the season can help disrupt their life cycle.

Good luck!

Garden tips

·        Remain alert for insect damage. Add spider mites to the list. Foliage of most plants becomes pale and speckled; juniper foliage turns a pale yellowish color. Shake a branch over white paper and watch for tiny specks that crawl. Watch for first-generation fall webworm.

·        Some pests can be hand-picked without using a pesticide. Do not spray if predators such as lady beetles are present. Spraying insecticides early in the morning or late in the day will avoid spraying honeybees and other essential pollinators.

Soil Tests Help Select a Fertilizer

Tom Ingram: Ask a Master Gardener

Sunday, June 7, 2020

Q: With all the different fertilizers out there, how do I know which one I should be using? AR

A: Fertilizers can be confusing. They come in a variety of strengths with a variety of numbers and for the beginner or novice, it can be overwhelming. So let’s break it down.

The fertilizers you find at the store have a series of numbers on the bag. These numbers can be something like the following: 10-20-10, 19-19-19, 3-17-17, 31-0-4, 46-0-0, etc. Those numbers coincide with the percentage of nitrogen, phosphorus, and potassium in each particular product. So, if a product says it is 10-20-10, that means it contains 10% nitrogen, 20% phosphorus and 10% potassium. If it says 46-0-0, that means that it contains 46% nitrogen, 0% phosphorus and 0% potassium.

So how do you know which one you should use?

The best way to know for sure is to have your soil tested. This may sound a little intimidating, but it is a simple process.

First, you will need to collect the soil sample. You can collect this sample using a specialized soil sampling tool or just use a garden trowel. A bulb planter works well also. The trick is to get between 15-20 samples from the area you want tested. These samples need to contain soil to a depth of 6 inches. If this is your yard, get 15-20 samples from various points in your yard, put them in a bucket, mix it up, remove the twigs and fill something about the size of a sandwich bag from the soil in your bucket. If you are wanting a soil test for your vegetable garden or your flower bed, get your 15-20 samples from those areas.

Once you get your soil sample in a bag, bring it to the OSU Extension office, 4116 E. 15th St. Even though the office is closed, there is a black mailbox on the south side of the building (in the back) where you can fill out a form and leave your sample. There is a $10 charge for a soil test. We will pick it up and forward it to OSU, where they will test for pH, nitrogen, phosphorus and potassium. Once tested, you will get a recommendation on what nutrients are needed for your situation. These recommendations will vary depending on what area you are sampling and what you are growing.

Once you have the results of your soil test, you will know how much of each nutrient you need to add to your soil for best results.

So back to the fertilizer. Let us say the test revealed your soil only needed nitrogen, and it was recommended that you add 1 pound of nitrogen for every 1,000 square feet. In this case, you could purchase some 46-0-0 fertilized because it is 46% nitrogen and does not contain phosphorus or potassium. This means that if each pound of fertilizer is 46% nitrogen, you would need about 2 pounds of fertilizer to give you 1 pound of nitrogen. If you purchased 10-20-10, you would need 10 pounds of this fertilizer to give you the 1 pound of nitrogen. Plus (in this case) you would be purchasing phosphorus and potassium that you didn’t need and which might also be harmful to your growing environment.

Yes, you may need to use a calculator, but odds are that getting a soil test will not only be good for your soil but also will ultimately help you save money by not having to purchase nutrients you don’t need.

Garden tips

•Do not work soil if it is too wet. Tilling it while wet will cause damage to the structure and it will take a long time to recover.

•Thatch is a layer of dead and living stems, shoots and roots which pile up on top of the soil at the base of lawn grasses. If it is over ½ thick it should be removed with either a core-aerator or power-rake. Now is the time to de-thatch Bermuda and zoysia. De-thatch fescue, if needed, in the fall.

Non-infectious Tomato Problems

Brian Jervis: Ask a Master Gardener

Thursday, June 4, 2020

Most of us have had our tomatoes in the ground for a while and are looking forward to some delicious fruit soon. However, our journey from planting to eating typically comes with a few challenges.

Tomatoes can be persnickety. Everything has to be just right to get fruit and then when things are going great, along comes an insect or a disease to frustrate your efforts.

We will talk about some of those issues in future articles, but first, let us talk about noninfectious diseases in tomatoes because most of these are the result of some sort of environmental challenge.

Blossom drop: Here is the scenario. Our plants are in the ground, we are getting flowers, and we are looking forward to those flowers developing into fruit. But instead, those flowers fall off and drop to the ground … thus the name “blossom drop.” Typically, we see blossom drop when we have settled into regular daytime temps above 90 degrees, as this heat inhibits pollination.

However, cooler temperatures can also contribute to blossom drop when our night temperatures are below 55 degrees. We have had weather like that recently, and some of you have been experiencing blossom drop due to cooler temperatures. However, once it warms up, you should begin to get fruit on your tomatoes.

Blossom-end rot: Blossom-end rot is pretty easy to spot when you notice the blossom-end of your tomato turning brown. Gradually, the brown spot gets bigger, is sunken and feels somewhat leathery. This area of the fruit then becomes susceptible to pathogens that result in the fruit rotting.

Blossom-end rot can be the result of several different factors; high temperatures, wind, fluctuating water availability and drought can all promote blossom-end rot. But so can excessive soil moisture for prolonged periods of time. These conditions inhibit the plant’s ability to draw up calcium from the soil, and so blossom-end rot is ultimately the result of a calcium deficiency.

However, adding calcium to the soil is not a solution to the problem because no matter how much calcium you add to the soil, the environmental conditions have not changed, and the plant is still not able to lift those nutrients up into the plant.

There are a lot of solutions online to blossom-end rot suggesting putting eggshells in a blender and sprinkling them around your plants. This will eventually add calcium to your soil, but it will not help solve the blossom-end rot problem, only time and drier conditions will do that.

Catface: Catfacing is an interesting one in that it shows up as misshapen fruit with what appear to be scars. Again, this is another temperature-related problem that can occur when temperatures are below 58 degrees when the flower is being formed. Turf-weed pesticides that contain 2,4-D can also be a contributor if they come in contact with your plant.

These are some of the main noninfectious disease problems we see in tomatoes, but you can learn about more on our website (tulsamastergardeners.org) by looking in our Lawn & Garden Help section under vegetables.

Garden tips

• Yellow leaves on plants may be due to too much water in the soil. With the deluge of recent rain and the subsequent saturation of the ground, some plants may show damage, often yellow leaves on the lower part of plants. This occurs both in ornamental and vegetable plants.

• Commonly, yellowness is due to lack of iron or nitrogen in the soil. However, when the soil is saturated with water, oxygen is forced out of the air spaces and the roots suffocate. This prevents them from absorbing nutrients, resulting in the yellow appearance. As the soil dries out, this problem will correct itself.

• Some pests can be hand-picked without using a pesticide. Do not spray if predators such as lady beetles are present. Spraying insecticides early in the morning or late in the day will avoid spraying honeybees and other essential pollinators.