Photo by S. Rae CC-SA-2.0.


Common problems in Arkansas warm-season vegetable gardens

Story by Lisa D. Martin

Gardening is a very popular hobby in Arkansas. The thrill of growing fresh vegetables coupled with the success of being able to not only feed a family, but have produce to share with extended family and friends or sell at farmers’ markets and roadside stands is one that many just cannot resist. 

Tomatoes, peppers, squash, okra, beans, peas, pumpkins, and melons can be found in home gardens throughout the state. Because of the mild weather that much of Arkansas is blessed with, warm-season vegetables grow from late March through mid to late October, depending on the weather, such as cold and frost coming in late in the season. 

Gardening is not without its problems though. Common garden issues can be divided into three categories: pest issues (diseases, insects, and weeds); environmental issues (soil quality, weather); and other external factors (deer and other wildlife). Warm-season vegetable plants are susceptible to a wide range of diseases and insect pests, many of which can be relatively easily controlled through careful sanitation and diligent scouting. While everyone likes their garden to be as productive as possible, a true gardener knows that dealing with pests, poor soil, and any number of wildlife intrusions is just part of living off the land, so to speak. 

Fungal diseases – powdery mildew, anthracnose, late blight, to name just a few – are all rather common due to the fact that they are encouraged by warm conditions (75-85 F) and relatively high humidity. While each disease has its own signs, symptoms, and control measures, one thing they have in common is that they are all caused by a fungal organism that loves Arkansas spring weather. 

Powdery mildew affects a wide array of garden vegetables as well as landscape plants. It is characterized by white fuzzy patches on new leaves. Powdery mildew can be controlled by good sanitation: removing and destroying affected leaves. Crop rotation is another way to keep powdery mildew out of the garden. 

Anthracnose is also a problem with both vegetables and landscape plants. It appears as small, gray spots on the leaves. The stalks will have gray to brown elongated lesions with a black ring around them. Again, sanitation and crop rotation help reduce incidence of this particular issue and there are fungicides that can be sprayed to combat the problem as well. 

Late blight is a common problem with tomatoes and peppers. Late blight appears as brownish, water-soaked lesions on the leaves. A great way to combat late blight is to avoid overwatering. Sometimes Mother Nature gives more water than is really needed in spring so when heavy rains are in the forecast, it is best to cut back on irrigation. 

Photo by Scot Nelson CC-SA-2.0.
Late blight affects many warm-season vegetables. One symptom is the large stem lesions. Photo by Scot Nelson CC-SA-2.0.

While the weather cannot be controlled, planting resistant varieties, good sanitation practices, and crop rotation are your best bet for keeping diseases in check. If a gardener is not totally dependent on organic methods, there are a number of very effective fungicides on the market that will take care of the aforementioned diseases along with a host of others. 

Common insects problems of warm-season crops include aphids, squash bugs, cucumber beetles, and tomato hornworms. This is by no means a complete list of the insects that inhabit many Arkansas gardens, but these tend to be the ones that get the most attention. 

Aphids are small oval insects, usually lime green, though some may be brown, yellow, or orange, depending on the specific type. Aphids feed on plant sap, sticking their needle-like mouthparts into the plant tissue and sucking the sap out. Aphids can be a real problem because they have a wide variety of host plants and they can be tricky to spot when they are the same color as the plants. They also reproduce extremely rapidly, thus making them difficult to control. Organic controls, such as neem oil and insecticidal soaps, can be pretty effective at knocking the population back. Insecticides containing permethrin or bifenthrin as the active ingredient are also very effective control. 

Photo by S. Rae CC-SA-2.0.
Aphids are a common problem in many gardens. Because they reproduce quickly and prolifically, control can be difficult. Photo by S. Rae CC-SA-2.0.

Squash bugs and cucumber beetles are similar in many ways and affect melon, squash, and cucurbit crops that are so popular in Arkansas gardens. Squash bugs tend to be somewhat secretive, which makes them more difficult to locate. While the adults are rather large, their brown color helps them blend in to the garden. Cucumber beetles, with their black and yellow stripes, are a little more visible in the garden. Like squash bugs they are relatively large as adults. Picking the insects from the plants is one effective way to control them, but is rather time consuming. Pyrethrins and neem oil are organic control options, while insecticides containing carbaryl, bifenthrin, or cyfluthrin as the active ingredient are effective chemical controls. 

Tomato (and tobacco) hornworms are probably the most visible creatures in a garden, mainly because of their size and the “horn”. Hornworms will forage voraciously on warm days, leaving a trail of damaged foliage. Because the insects and the damage they cause are easily seen, the most effective control for this particular pest is removing the worms from the plant and disposing of them – either by “squashing” or dropping them into a bucket of soapy water. Wear gloves when removing by hand because they will “spit” a dark liquid when the feel threatened. 

Photo by Shane Darby.
Hornworms feed voraciously on foliage, leaving a trail of damage. Photo by Shane Darby.

Environmental conditions – such as soil pH, tilth, mineral deficiencies, and weather patterns – affect the garden; some gardeners can control, others, not so much. Soil pH can be adjusted. Most Arkansas soils tend to be on the acidic side and require at least a little bit of lime to bring the pH into a range that is suitable for common garden crops, somewhere between 5.8 and 6.5. It takes, on average, six to eight weeks after applying lime to see a noticeable difference, so liming should be done before planting. Mineral deficiencies can be addressed fertilizers. Have your garden soil tested through your local county extension office. The results will include soil pH and nutrient availability and recommended additions/remedies for optimal vegetable production. 

While pH and mineral levels can be changed, soil type and weather patterns are completely out of a gardener’s control. Gardeners just have to work with what they have and follow recommended practices.

Deer and other wildlife can sometimes have a devastating effect on a garden. In fact, if someone could invent a completely foolproof method to keep deer out of gardens, that person would become very rich very quickly. The main reason that deer and other wildlife invade gardens is that they are an easily accessible food supply. Physical barriers – tall fences for deer or underground fences for burrowing animals – are effective, but can be expensive and time consuming. Chicken wire, netting, or other cover allows plants to grow while making it more difficult for deer to reach the desired fruit. Some gardeners swear by so-called “scare tactics,” such as loud noises played on a loop, a barking dog, or even human hair. While these may be effective in some situations, deer, like other animals become accustomed to these tactics and soon begin to ignore them. Repellents that emit a foul odor or make the plants unpalatable can also be somewhat effective. The downsides are that they can be expensive and usually require frequent reapplication. 

Even gardeners that have the best soil, top-quality seeds and seedlings, and the greenest thumbs will face some kind of problem(s). But most gardeners learn early on that there is some level of imperfection to be expected when working with factors that are out of their control. 

Gardening is definitely a labor of love, as many gardeners will attest. Gardening requires patience, hard work, and a little luck, but most would agree that the “fruits of their labor” are well worth the time, energy, and effort.

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