169-Your Biggest Garden Challenges of Summer, 2020

Coming up on the middle of August, it’s clear that the 2020 gardening season is one for the record books — not for its performance, but for its challenges. Having been a gardener my whole life and in professional horticulture for more than 30 years, I can say that this was the year of all years for garden challenges. In this week’s episode, I answer questions that have come in this summer from podcast listeners, the members of the joegardener Facebook group and students in my Online Gardening Academy™ about their biggest gardening challenges this year so far. For some of these issues, there’s still time to mitigate the problems and get a better outcome, while others will be taken as lessons learned for next year. 

My goal is to give you some encouragement and to inspire you to keep fighting the fight, because I can sense your frustration — and even a little despair — in your comments and emails. 

Gardening can be very rewarding, but also very humbling. With those rewards come learning opportunities to become a better, smarter, more confident gardener. Those challenges help you to really appreciate the fruit — and veggies — of your labor. Gardening is not hard, but it’s also not easy, and that’s just the way I like it. If it was free of challenges, I’m not sure I would be as enamored by it. I’m sure many of you feel the same way.

There’s been a lot of talk in our social media channels this year about pepper plants. Among the garden challenges this season, it seems that many gardeners are experiencing slow growth with their peppers. Unusual temperature patterns can play a role in this phenomenon. (photo: Amy Prentice)

Sold Out! The First of the Garden Challenges of 2020

The earliest signal that new garden challenges were going to be in store this season came in March, as the coronavirus pandemic was just setting in. The desire to be self-sufficient led many experienced gardeners to redouble their efforts and many new gardeners to get their hands in the dirt for the first time. 

Mail-order seed companies saw orders pour in like never before, and some had to stop accepting orders entirely until the backlog could be fulfilled. Many seed varieties sold out, and the run on gardening supplies didn’t stop there: Seed starting lights and grow bags were also unavailable or back-ordered for weeks. Hopefully, you were able to get the supplies you needed most with adequate time to put them to work.

Managing Insect Pests 

Our own Amy Prentice, the Marketing and Communications Director here at Agrivana Media, shared that she had her first experience with armyworms on her tomatoes. Armyworms, like fruitworms, destroy tomatoes themselves. A third destructive caterpillar found on tomatoes is the hornworm, which eats the foliage of tomato plants. 

Armyworms are the larval stage of nondescript brown and white moths that lay their creamy, white, tiny little round eggs near the fruit or on the leaves of a tomato plant. The eggs are protected by white webbing that, if you see it, signals your about to be the parent of armyworms — and you don’t want that. Armyworms rarely bore deep into a tomato but they do leave irregularly shaped holes and scarring on the surface. 

There are a few common caterpillar pests that eat the fruits of tomato plants. These include armyworms which often feed externally on fruit. Tomato fruitworms typically feed inside the fruit. (photo: Amy Prentice)

Fruitworms enter deep into the green fruit when the tomatoes are young and small, around the stem area. The damage can cause the fruit to ripen prematurely, and then the fruitworms will move on to the next tomato. These are laid by brown-tan medium-sized moths that lay just a single egg on top of or underneath a tomato leaf.

Hornworms are fat green caterpillars with a horn-like protrusion on their back end. They are sometimes seen covered with white parasitoid wasp cocoons that look like grains of rice. 

To mitigate the damage from armyworms, fruitworms and hornworms, you need to regularly examine your tomato plants when they are still growing. If you see the telltale little holes in leaves or fruit, you need to take action. (In the case of hornworms, they eat the leaves completely, right down to the stem.) 

Manual removal is your first control, as an organic gardener. Another organic control option is an application of Bacillus thuringiensis, or Bt, a biological control that only affects caterpillars and won’t harm other insects. Just use caution when applying Bt around milkweed (or any other butterfly larva host plants), where it will kill feeding monarch and other caterpillars.

Susan B. writes that she has never had so many bug infestations over one season, from wooly aphids on her shrubs to sawflies devouring her roses, and Cindy T. is likewise dealing with Japanese beetles on her beans. 

Japanese beetles are a nice looking insect, with a bronze, metallic green sheen, but they are also very destructive. Their trademark damage is leaving foliage looking like lace. 

My method of choice for controlling Japanese beetles is going out early in the morning with a cup of soapy water and just knocking the groggy beetles in the cup before they are up and alert for the day. I don’t recommend Japanese beetle traps with lures because they are too effective — they attract more beetles than the traps can hold, and you end up with more beetles in your yard than you had before. Instead, I recommend Bacillus thuringiensis galleriae, or Btg, an organic, selective pesticide that won’t harm people, pets and non-target beneficial insects. Btg can be applied on foliage to kill adults or on the soil to kill the grubs before they emerge. 

Alternatively, you can add parasitic beneficial nematodes to your soil that will kill Japanese beetle grubs before they reach adulthood. Nematodes are basically microscopic worms that feed on specific organisms. The nematodes that are most effective against Japanese beetles are Steinernema glaseri and Heterorhabditis bacteriophora. To learn more about nematodes, check out my podcast episode with Dr. William Crowe.

As a non-native pest with no natural predator, Japanese beetles proliferate easily and are difficult to control. Simply tapping them into a jar of soapy water during an early morning stroll in the garden can be quite productive as reducing beetle populations.

Jill G. is confronting aphids in her garden. Aphids show up in early spring and, while the individuals are small — around an eighth of an inch — they start to establish large colonies on your plants. 

Aphids cause damage by piercing the plants and sucking out the sap. Even though plants can tolerate a lot of this damage itself, the aphids are also vectors for plant diseases. 

The two most common aphids you’ll see are the pear-shaped pink aphid called the potato aphid and the pear-shaped green aphid with a yellowish tint called the green peach aphid.

Aphid damage can appear to be a sign of disease on top of leaves. Before needlessly applying a disease control, check under the leaves for aphids or other bugs that have been causing piercing damage. 

Bean beetles often eat away at tissue from the undersides of the leaves which can cause foliage to appear diseased. It’s a good practice to turn over leaves that look infected by disease to see if an insect pest is actually the culprit.

There are a lot of predators that will control the aphid population for you, most notably lady beetles. Lady beetle nymphs — they look like tiny red and black alligators — are actually more voracious eaters of aphids than adult lady beetles. 

A few other predators include Syrphid fly (hoverfly) larvae, damsel bugs and tiny wasps. You can intervene yourself with a sharp blast of water to knock aphids off your plants. To them, it’s like a blast of water from a fire hydrant. Insecticidal soap is another organic control, but it is nonselective, or broad-spectrum, and will kill beneficial soft-bodied insects that come in contact with it by desiccating them. 

You may not recognize this insect, but it’s actually the larval stage of the much-loved ladybug or lady beetle. If you look closely, you can see that it’s devouring a green peach aphid. Ladybugs are voracious eaters at this stage and a natural enemy of aphids and other sap-feeding insects. (photo: Amy Prentice)

Cucumber beetles have taken up residence in the garden of Whitney H. this season, and the population is just exploding despite her chickens helping her efforts to keep them in check. 

The two most common cucumber beetle species are the striped cucumber beetle and the spotted cucumber beetle, with the former being the most problematic. The adult striped cucumber beetle is about a quarter to three-eighths of an inch long, and yellow with three black stripes down its back and a black head and antennas. The spotted cucumber beetle is similar but with 12 black spots on its wing covers. 

Both species can be found on cucurbits — hence the name cucumber beetle. But that includes squash and melons also. 

The striped cucumber beetle not only causes damage to foliage, but it also carries a bacterial wilt pathogen that particularly affects cantaloupes and muskmelons.

Both cause damage to foliage and fruit, but the striped cucumber beetle is of more concern because it carries the bacterial wilt pathogen which affects the plant’s vascular system — basically the plumbing. Cantaloupe and muskmelons are the most severely affected by bacterial wilt. 

Once the plant is infected, it’s done. The wilt will spread rapidly over a couple of days. A white ooze like Elmer’s glue in the stems is a sign of wilt. You’ll want to remove that plant before beetles can pick up the bacterium and spread it to other plants. 

To control these beetles, remove the leaf litter from your garden where they lay their eggs, and put down mulch. Also, remove weeds that are often host plants for plant diseases. A physical barrier over your plants, such as row cover or tulle (bridal veil), will keep beetles from landing on your cucurbits. However, you will need to hand-pollinate because pollinators cannot reach your plants when you’re using row cover. You can resort to neem oil as a control, but neem oil, much like insecticidal soap, is not selective.

Use discretion when you see insects in your garden: 97% are beneficial or neutral, and the 3% that do qualify as pests rarely, if ever, justify broad-spectrum lethal controls. 

Row cover is a type of physical barrier that is effective in preventing many insect pests from reaching plants. Light, air, and water still get through while pests are kept out.

Managing Plant Diseases

Many listeners have reported that plant diseases are especially bad in 2020, including some they have never seen before. This is because of the “disease triangle,” the three components that are necessary for a disease to present itself. These are the pathogen, the host plant and the right environmental conditions. When all three are present simultaneously, you will get a diseased plant. And the more favorable the environmental conditions are for a disease, the more severe it will be. 

So what’s different this year? I believe it’s that environmental conditions were ripe for disease. Still, you can minimize the spread of disease by adopting sanitary practices in your garden, such as cleaning your pruning tools with alcohol between cuts and removing diseased plants and plant parts from the garden completely and disposing of them properly — not in the compost pile. By watering plants at ground level rather than on the foliage, you can avoid creating a wet or humid environment where many plant diseases thrive.  

Watering at the ground level rather than overhead helps prevent disease pathogens from taking hold on plant foliage.

When removing diseased foliage from a plant (a key sanitation practice), you may feel that there’s hardly any plant left. However, plants can still produce even when they have lost a significant amount of foliage. Tomato plants are a classic example of this.

There are three types of plant diseases: bacterial, viral and fungal. About 85 percent of the diseases you’ll see in your garden are fungal. Once a plant is infected, it’s infected. There is nothing you can do to eliminate it from a plant completely. You’re just in a race against time to harvest fruit before the plant is a complete loss. 

You can take the proactive step to treat plants with a fungicide before they become infected if you know fungal problems are in store for your garden. The organic approach is to use a copper fungicide, which is somewhat effective, but know that copper is a heavy metal that will build up in the soil when used frequently or excessively. A synthetic option is Daconil, the active ingredient of which is chlorothalonil. Practice discretion to avoid runoff when applying any fungicide and always follow the instructions on the bottle. 

Another proactive measure is to look for plant varieties that are bred to be resistant to the diseases that have caused your trouble. Look on the plant tag for the letters that indicate what diseases the plant resists. Some examples include:  V for verticillium wilt, F for fusarium wilt, N for nematodes, T for tobacco mosaic virus and A for alternaria.

Once disease starts to show up on the foliage of tomatoes and other crops, it’s best to cut away the affected branch and remove it from your property. While it won’t cure the plant entirely, it will slow the progression. And removing it from the area will help prevent its spread to other plants.

Managing Birds and Mammal Pests

Are birds pecking your ripe tomatoes? There is a simple fix. If you pick tomatoes at the “breaker stage,” when they are about halfway to full ripeness, they will finish ripening indoors. While people are skeptical until they try it themselves, I can assure you that your tomatoes will finish ripening off the vine. 

You can keep birds and chipmunks out of your garden with a motion-activated sprinkler. These are great at keeping animals away — but remember it’s there before strolling into the garden yourself and getting wet.

These animals are generally looking to enjoy the water in tomatoes rather than the tomatoes themselves, so making a source of fresh water available may deter them from going after your vegetables. 

Birds will typically peck a tomato at the point of ripeness. They are usually more interested in the water inside the fruit rather than the fruit itself. One way to help prevent bird damage is to harvest the tomato at the breaker stage before it can become red, juicy, and desirable to the thirsty birds who visit the garden.

If you haven’t seen what’s foraging in your garden, a wildlife camera is a great tool to have. These motion-sensor cameras are capable of recording video at night. You’ll be surprised to see who’s been visiting in the dark, and knowing will enable you to implement the appropriate controls.

Gophers are troublesome, and the only effective control I know is a physical barrier. Not only should a barrier go around the perimeter of your garden, the barrier — hardware cloth is one example — should extend outward too. This will stop gophers before they can even begin to dig under your garden.

For pests like gophers, you can add hardware cloth under your raised beds or at the base of a fence surrounding your garden. I buried 6″ attached to my fence when I built the GardenFarm. Hardware cloth is an effective barrier because it’s made of metal and pests can’t chew through it.

Slow Growing

Unusually slow growth with very little production is another common issue listeners have reported this year, and the problem has been especially prevalent in cucumbers, squash and peppers this year. 

The five main conditions that affect plant growth are light, water, nutrition, humidity and temperature. I want to key in on temperature, which has been unusually cold or unusually hot at different times this year around the country. 

Overall, temperature influences most of the basic processes that a plant goes through as it’s developing, including photosynthesis, transpiration and respiration. It also affects when a plant germinates and when it flowers. 

As temperatures go up, photosynthesis, transpiration and respiration increase. When you combine that with increased day length, the temperature also affects plants going from a vegetative or leafy state to a reproductive state, when they’re starting to flower and fruit. 

Depending on the plant and where it is in its growth cycle, temperature can either speed up its growth or slow it down, or slow down the transition. 

Temperature can also explain why tomato plants aren’t setting fruit. When temperatures rise above 90 degrees or when nights stay above 75, pollen can become unavailable. High humidity can make pollen so sticky that it doesn’t fall. Conversely, dry conditions can make it so pollen falls but doesn’t stick at all. Because tomato flowers are self-pollinating —they have both male and female parts in the same flower — you can help them along by shaking the plants to release the pollen. 

Cucumbers and other vertical growing crops have been slow to grow this year for many gardeners. Several gardeners have told me that their arbors and trellises are barely covered this year. (photo: Amy Prentice)

Remember, there’s always next year. I hope you have found some of this to be helpful and interesting, and that it is applicable to you now or will be helpful in the future. If you haven’t listened to this week’s episode yet, you can scroll up the page and click Play icon in the green bar. Have you had garden challenges in 2020? Share your story in the comments below. 

Links & Resources

Episode 005: What’s Wrong With My Tomato? Mid-Season Care With Craig LeHoullier

Episode 008: Organic Pest Control, with Jeff Gillman

Episode 044: Raised Bed Gardening, Pt. 3: Animal Control & More

Episode 050: Organic Pest Control: Beneficial Insects And Beyond 

Episode 060: How to Control Nuisance Wildlife in the Garden: Deer, Rabbits, Moles & More

Episode 067: Predatory Beneficial Insects: Feared Foes of Garden Pests

Episode 115: Understanding Tomato Diseases and How to Deal With Them

Episode 144: Understanding Nematodes: Microscopic Worms, Friend or Foe of Your Garden

Episode 162: Plant Disease Fundamentals: Understanding the Basics and Beyond

Episode 167: Managing Plant Diseases Organically, with Jeff Gillman

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