It’s been a challenging spring in this guy’s garden! Despite getting the normal early start required for successful gardening in Florida, I’ve been affected by Bacterial Leaf Spot stunting my tomatoes, cutworms that reduced my watermelon plantings by half, and an eternal test of my patience in the form of a dog that seems to think my raised beds are merely a shortcut to a destination further out in the yard. My latest adversary is the most potentially destructive yet, an outbreak of Southern Armyworm (Spodoptera eridania).
Early Southern Armyworm damage on Okra seedlings. Photo courtesy of the author.
Unlike some serious garden pests that wait until the heat of summer to emerge, Southern Armyworms begin appearing in spring gardens around the end of April. Adult moths can survive mildly cold weather and venture into the Panhandle as soon as warmer spring weather arrives. Once the adult moths arrive, egg masses are then laid on the undersides of leaves and hatch in a little under a week. Once loosed upon the world, Southern Armyworm larvae (caterpillars) become indiscriminate, voracious feeders and congregate in extremely large numbers, allowing them to destroy small, developing garden vegetable plants in a manner of days. Young larvae feed on the undersides of leaves and leave little but a skeleton. As larvae grow larger, they become solitary and begin to bore into fruit. Once they’ve eaten the good stuff (leaves and fruit), large larvae turn to branches and even plant stems!
Southern Armyworm larvae feeding on Okra leaves. Photo courtesy of the author.
The good news for gardeners is that Southern Armyworm, and most other caterpillar pests, are easily controlled if outbreaks are caught early. Scouting is critical for early detection and good control. Armyworm damage generally appears from above as brownish-gray sections of affected leaves with a yellowish ring surrounding these sections, this ring indicates the current feeding zone. Affected areas will appear transparent and “lacy” due to the skeletonizing effects of larval feeding. If you see leaves that look “off” in the manner just described, check underneath for the presence of a horde of tiny greenish worms.
If found in this early stage, an application of Bacillus thuringiensis (Bt), a biological pesticide utilizing a bacterium destructive to caterpillars, is extremely effective. Bt has to be ingested by caterpillars with leaf tissue to work; thorough coverage of leaf surfaces is critical for maximum control. I generally follow up with a sequential application of Bt a day later to ensure that I achieved good coverage of the plant surfaces and, therefore, good control. Unfortunately, Bt is much less effective on older larvae. Infestations not caught early require harsher chemistries like carbamates, pyrethroids and organophosphates for adequate control.
Don’t let armyworms or other caterpillar pests destroy your garden, get out there daily and scout! You have a short window for easy caterpillar control with a harmless to people, natural product, Bt. Don’t waste it!
For more information about Southern Armyworm, other caterpillar pests, Bt, or any other horticultural topic, please consult your local UF/IFAS Extension Agent. Happy Gardening!
Adult squash vine borer moths are easy to identify, as they are reddish orange and have black dots along their upper abdomen. Photo by Theresa Friday.
It’s been a few weeks, and your squash seedlings are really starting to take off. The days are blushing with summer warmth and the flicker of lightning bugs in the evening indicates the cool nip of spring is winding down. In your garden, this has culminated in lengthening cucurbit stems that now show off a beautiful bright shade of green. Squash blossoms appear overnight and begin to expand and take shape, nestling themselves under the backdrop of slightly darker green squash leaves.
Black beauty zucchini blossom in the morning sun. Photo by Molly Jameson.
A few more nights go by, giving you a chance to explore some recipes. Maybe it’s time to fire up the grill and make grilled summer squash, sprinkled with fresh mint or thyme. Perhaps you’ll make a summer squash pesto pizza. Afterall, your basil is ready for its first harvest. If you are ahead of the game, you might even have some vine-ripening tomatoes that would pair nicely with squash in a creamy pasta sauce.
Your culinary dreams are running wild when you start to notice the wilt. You panic, and think you’ve forgotten to water the garden. But no, you’ve given your garden a consistent dose of water every morning. Your basil looks fine. Your tomatoes look great. What is going on?
Squash vine borer adult in flight. Photo by Molly Jameson.
You have fallen prey to the dreaded squash vine borer (Melittia cucurbitae).
These garden pests rely strictly on plant species within the genus Cucurbita. If the squash vine borer didn’t wreak such havoc in your summer garden, you might find its striking red and black features fascinating. Unfortunately, if your squash plants are wilting unexpectedly, this daytime roaming moth may have already done its damage.
Adults lay single reddish-brown, millimeter-long eggs on the lower end of the main stem – or on leaves, leaf stalks, fruit buds, or in the soil near the squash plant. Within one to two weeks, larvae hatch, bore into the stem of healthy cucurbits, and begin to chew their way up. Multiple larvae can infect a single plant. This blocks the transport of water and nutrients, leading to the dreadful wilt that often signifies that it is too late.
A squash plant severely damaged by squash vine borer larvae. Photo by Molly Jameson.
So, what can be done? Once the wilting has begun, you may be able to reap a small harvest, depending on the timing of infestation. Adult females emerge from cocoons from May to October in Florida and have two generations per season. They prefer cucurbit varieties with large tubular stems, such as yellow squash, zucchini, and pumpkins, but can also infest watermelon and cucumbers.
If you have some cucurbits that do not show signs of infestation but others that are on the decline, it might be worth removing and destroying the infested plants. At the end of the season, cultivate your soil one to two inches deep, as this is where they overwinter in cocoons. Destroying infested plants and cultivation can help reduce the overwintering population.
Squash vine borer larvae inside a squash stem. Photo by Molly Jameson.
In North Florida, try seeding squash indoors in March and plant seedlings in the garden in early April. The earlier you plant, the better chance you have of beating the borers. Of course, you must balance the risk of borers with the risk of a late frost.
You may also want to install lightweight floating row covers that can prevent the female from depositing her eggs. But again, it’s a delicate balance, as you do not want to prevent beneficial insects from pollinating your squash once it is producing blossoms.
Scout your plants diligently each day and keep on the lookout for eggs and adults. Adults are attracted to the color yellow, so yellow sticky traps or yellow bowls of water may lure them in. Build up the soil around developing plants to act as a shield against egg laying and boring.
A healthy straightneck squash plant beginning to set fruit. Photo by Molly Jameson.
Once your plants slow their fruit production and you’ve had your fill of grilled squash, squash pizza, and creamy squash pasta, go ahead and remove the plants to prevent late infestations that can then overwinter. Lastly, rotate areas in which you plant cucurbits each year to break borer life cycles.
Vegetable gardening involves innovation and ingenuity. A clever gardener is always striving to balance weather, timing, insects, plants, soil, and everything in between. With a little planning and persistence, I know you can prevail against the tenacious squash vine borer.
For more information about squash vine borers, check out the UF/IFAS EDIS publication, Squash Vine Borer Melittia cucurbitae (https://edis.ifas.ufl.edu/in1068).
Early BLS symptoms appear on lower leaves. Photo courtesy of the author.
Tomatoes are among the most notoriously difficult vegetable species to grow in Florida. Even when you do everything right (choose disease resistant varieties, buy clean seed/healthy transplants, plant early, rotate crops, scout for insects, prune and support vines, etc), things can go wrong in a hurry. Bacterial Leaf Spot (BLS) caused by the pathogen Xanthomomas perforans, is one of those things. BLS often hitches a ride into gardens undetected on seed and transplants and presents itself as warm and humid weather arrives in late April/early May. Outbreaks typically happen in concurrence with the frequent heavy rainstorms that accompany these months and quickly wreak havoc on tomato plants.
BLS occurrence, much worse in some springs than others, has exploded this year in home gardens. First noticed on the plant’s lower leaves, BLS pathogens enter through natural openings in leaves called stomata, manifest as small, “water-soaked” leaf lesions and then develop within days into dark circular spots, sometimes surrounded by a yellow halo. As conditions worsen, all these individual infections cause a general yellowing or “blighting” of entire leaves. Though the issue begins on tomato leaves, BLS can affect all parts of the plant, including stems, flowers and fruit too! It’s at this point, when blighted leaves become obvious and lesion developing on flower stalks cause both flowers and small fruit to drop, that most home gardeners notice that something is up.
Advancing progression of BLS with “blighted” leaves. Photo courtesy of the author.
Unlike with many other pathogens, gardeners don’t have an abundance of options to control BLS. However, taking the following preventative measures can reduce the pathogen’s impact and stave off disease progression until ripe fruit can be harvested.
- Don’t irrigate overhead. Utilize drip/microirrigation or hand water beds and containers at soil level. This prevents the leaves from becoming wet; wet leaves become a perfect host for BLS.
- Never work tomato plants when leaves are wet. No staking, pruning, tying, or anything else until plant tissue is dry. Working wet tomato plants is an excellent way to spread bacteria!
- Sanitize pruning tools often and wash hands after working infected plants.
- Maintain airflow in plants by planting at correct spacing and thinning interior leaves as necessary to facilitate quicker drying of the plant.
- Prune lower leaves to at least 12” from the soil’s surface to prevent disease transmission from soil to leaves through splashing water.
- Remove infected leaves (when plants are dry!) to slow disease progression.
- Rotate crops and destroy infected plants to prevent buildup of BLS organisms in soil.
BLS lesions on tomato flowers. Photo courtesy of the author.
- Preventative measures are best, but if your garden has a history of BLS and local weather forecasts call for warm/wet/humid weather, it is best to spray fungicides proactively to protect your crop. A weekly spray with a tank mixture of copper and mancozeb is effective at keeping BLS at bay. This is the only chemical spray combination proven to be effective in controlling BLS.
- Unlike many common tomato pathogens that can be reliably avoided through planting resistant cultivars like ‘Big Beef’, ‘Celebrity’ and others, no varieties are resistant to BLS.
While BLS is an extremely destructive pathogen of both home and commercially grown tomatoes, growers can lessen the disease’s effects by following the preventative measures outlined above and spraying with a copper/mancozeb mix if necessary. Growing tomatoes this year hasn’t been easy, but it’s worth it to fight back and realize a harvest despite difficulties like BLS!
If bacteria have given you the blues or other garden issues are bringing you down, give your local UF/IFAS County Extension Agent a call! We’re here to help you be successful in all your horticultural endeavors. Happy gardening!
‘Multipik’ fruit. Photo courtesy the author.
Never one to be satisfied growing “standard” vegetable varieties, last year I decided to peruse various seed sources in search of a superior yellow summer squash selection. Plain ‘Yellow Crookneck’ just wasn’t doing it for me anymore. After doing a little research and consulting a friend who works for Johnny’s Selected Seeds, I settled on a straightneck variety called ‘Multipik’.
Developed in the 1980’s by Harris Seed and now sold by many seed purveyors, ‘Multipik’ enjoyed immediate popularity with commercial squash growers due to its many outstanding qualities but curiously, is just making inroads with the home garden market. Even as it is set to celebrate its 30th anniversary next year, two years of personal experience with ‘Multipik’ verify several important characteristics making it a superior choice to many other traditional summer squash varieties: earliness/heavy yields and a precocious gene.
Newly developing ‘Multipik’ fruit. 4 weeks after planting. Photo courtesy the author.
The longer I garden, the more I’m convinced that earliness to maturity is directly related to yield potential in home gardens, especially in the Panhandle. Lots of varieties have high yield potential but that potential is often at least partially wasted here due to the length of time from seed to harvest. Ideally, you could plant, grow a crop and be done by mid-late June, before intense heat, humidity and all the wonderful garden pests and diseases arrive to destroy spring gardens. Maturing just 50 days from planting, ‘Multipik’ beats that deadline (when planted on time in late March) and yields heavily for at least a month before succumbing to the harsh Panhandle summer. Many traditional summer squash varieties, including ‘Yellow Crookneck’ mature 8-14 days later. While 8-14 days doesn’t sound like much, it can mean a major yield difference when factoring in the almost certain late season pests, diseases, and adverse weather conditions.
The next major advantage ‘Multipik’ offers is a precocious gene, meaning that it will mask symptoms and maintain its yellow color if infected with either Watermelon Mosaic Virus (WMV) or Cucumber Mosaic Virus (CMV), two destructive pathogens commonly affecting squash by discoloring fruit and reducing yield. This trait is critical to commercial growers because yellow squash that isn’t yellow isn’t marketable and is important to home gardeners too as a means to eke out higher yields under virus pressure. While the precocious gene isn’t a cure for either virus, it can help hold them at bay while you harvest! Another quirk caused by the precocious gene is the all-yellow appearance of the fruit, from the peduncle (the stalk holding the fruit to the plant) to the apex! From one end of the fruit to the other, Multipik ensures that when you plant yellow squash, you harvest yellow squash.
‘Multipik’ just days from harvest. Photo courtesy the author.
Whether you are trying to avoid yield loss from late season insect and disease pressure plaguing your traditional squash plantings or just want to try something a little different, I highly recommend planting ‘Multipik’ Squash. This early, disease-resistant cultivar with delicious medium sized, light yellow fruit is sure to be a hit in both in the garden and on the table. As always, if you have any questions about vegetable gardening or any other horticultural topic, give your local UF/IFAS County Extension Office a call! Happy gardening!
Cucumbers are a favorite fruit of many gardeners and with a little routine care, you can harvest fresh fruit from your own home garden. Learn some basic information about starting your own cucumbers In the Backyard Garden with UF IFAS Extension Escambia County.
During the COVID-19 crisis, many of us have found that we have more time for activities at home. One activity that can be beneficial to your mental and physical health is gardening. Not only will gardening get you moving physically, but simply being outdoors can help you feel more relaxed during these stressful times. By vegetable gardening, you get the added bonus of becoming more self-sufficient by growing your own healthy food.
You can still gather your gardening supplies at local garden centers during COVID-19. Photo by Brenda Buchan.
To grow vegetables successfully, you will need some basic gardening supplies. This includes seeds or seedlings, fertile soil, gardening tools, and irrigation materials. If you are an avid gardener, you may already have these items at your house. But if you are new to gardening – or if you are simply missing an essential item in your everyday gardening arsenal – where do you go?
Thankfully in Florida, industries regarded as essential during these tough times include food, agriculture, and infrastructure support services. This means farmers, farm workers, farmers’ markets, produce stands, food banks, agribusiness support services, and landscaping services can continue to operate.
But for these essential services to operate safely, they still need to follow social distancing principles to protect the health of both their customers and workers. Therefore, many of our agriculture and horticulture industry personnel are finding ways to adapt. Although this involves making many adjustments, operations such as garden centers and plant nurseries are changing how they function to meet the demand of their customers while remaining safe.
Become more self-sufficient by growing your own healthy food in your backyard. Photo by Molly Jameson.
For example, Native Nurseries in Tallahassee has temporarily closed its doors to the public, but they offer pickup and delivery options that are consistent with social distancing guidelines. Customers can either email or call the nursery and provide their contact and billing information, their purchase requests, and specify either pickup or delivery. Pickup orders are placed in a labeled designated parking space for the customer. For a fee, Native Nurseries also offers delivery of purchased items.
If you plan to make a trip to a garden center or plant nursery, call ahead or check the company’s website to learn about its social distancing policies, pickup and delivery options, and any potentially reduced hours of operation.
By continuing to support our local agriculture and horticulture businesses, we can ensure that they can weather this storm and continue to provide us with their essential services long into the future.
So, gather your supplies, stay home, and get your spring and summer vegetable garden growing!
For more information about essential services in Florida, visit: https://www.floridadisaster.org/.