Heather Kirk-Ballard, Heafner, Kerry, Singh, Raghuwinder, Strahan, Ronald E., Fontenot, Kathryn, Fields, Jeb S.
July and August are our hottest months. The dog days are upon us! Even the breezes are hot! Garden chores during these soupy, summer months are mounting. So, put a sprig of spearmint in your iced tea and let’s get to it!
Just as heat, humidity and lack of adequate rain can be hard on turfgrasses, so can watering too frequently. To conserve water by avoiding runoff and to prevent fungi from being problematic, water lawns less frequently, but deeply, for longer periods at a time. This will promote a healthy root system and allow turfgrasses to be more resistant to pests. Water to a depth of 6 to 8 inches (1 to 1.5 inches of water) once a week. Water between 4 and 8 a.m. to allow residual water to evaporate during the day. Southern turfgrasses will let you know if they need a drink. Look for leaf blades curling inward and turning dull gray. Also, if walking across your lawn produces foot imprints that remain, then water is necessary. Less frequent mowing will also help lawns weather the summer months. Raise the blade on your mower by an inch. More shoot systems above ground will mean more healthy roots below ground. And these roots will be able to reach water nutrients more efficiently.
Both heat and pests can take a toll on warm-season annuals. Try deadheading, or snipping off spent blooms, to encourage new growth and a second flush of color. A reapplication of a slow-release fertilizer may also be necessary to help reinvigorate a tired-looking flower bed. Water flower beds deeper and less frequently. If possible, use either drip irrigation or soaker hoses. This way, water is delivered exactly to where it needs to go, the roots. Keeping unnecessary water off the foliage will keep fungal problems at bay. Pests to watch out for during these months include, among others, the canna leaf roller on canna lilies and aphids on a variety of plants. If insecticides are used, read, understand and follow the information and directions on the insecticide’s label. Keep tropical hibiscus looking good by removing spent blooms. Do the same for native hibiscus. August is the month for dividing irises. When replanting iris rhizomes, provide a layer of mulch to help retard water evaporation from the soil. Members of the composite or sunflower family are at peak bloom now. Blanket flower (Gallardia sp.), tickseed (Coreopsis sp.) and Mexican sunflower (Tithonia sp.) should all be buzzing with bees and butterflies.
Start seeds for fall tomatoes and cool-season cole crops now. They should be ready to transplant by late August or early September and should produce until the first frosts in late November or early December. Okra should be going strong during this hottest time of the season. Cut pods when they’re tender to keep plants producing. If growing an open-pollinated variety, save seeds for next year by leaving a pod or two on each stalk and let them mature until they dry and start to split open. Field peas (purple hulls, crowders, etc.) should still be going strong. Another planting may be made so production occurs well into fall.
These hot summer months are stressful for trees and shrubs if rains are not consistent. Even the largest trees in the landscape need water. If you water trees, remember that feeder roots are not up close to the trunk of the tree. Rather, they extend out away from the trunk and end approximately where the branches end. This is called the drip line. As with lawns, watering deeply and less frequently will be benefit trees if rains are several weeks apart. Water should be applied slowly and should reach a depth of 12 to 15 inches. Native species will be better adapted to often-unpredictable precipitation in our area during these months. Willow oak (Quercus phellos), southern sugar maple (Acer barbatum) and sweetbay magnolia (Magnolia virginiana) will all withstand hot summers.
Associate Extension Agent in Horticulture
In this article:
|Announcing the 2022 Louisiana Super Plant Inductions|
|Checklist for June, July, August|
|Bountiful Vegetable Gardening|
|Tips for Summer Care of Turfgrass|
|Leaf Spot and Fruit Rot of Strawberry|
From the persistence of COVID-19 to record-breaking natural disasters, 2021 presented numerous challenges to us all. The green industry has experienced its share of unique problems, too, often making it difficult to find the exact cultivar to stock in the nursery or plant in the landscape. With this in mind, we are hoping to make Louisiana Super Plant access a bit easier with the 2022 selections, all of which provide a bit of flexibility in this ever-changing time. This doesn’t mean the superiority of the plant material is compromised, though! Each of the 2022 Louisiana Super Plants has been rigorously tested and vetted by the LSU AgCenter and members of the industry to be a perfect fit for every Louisiana landscape!
Spring 2021 proudly welcomed the addition of Louisiana iris to the Super Plants program. Native plants, such as the Louisiana iris, are well-suited to handle the wild weather swings we can experience in Louisiana. There are myriad flower colors and sizes to choose from, all of which attract a wide array of pollinators. Irises prefer full sun and typically bloom from late March through April, going dormant in the hot and dry late summer weather of August and September. Once temperatures cool off in November, Louisiana iris plants will once again start growing and provide striking sword-like green foliage throughout the winter when most other garden plants have gone dormant. Louisiana irises are highly adaptable plants that can make beautiful additions to water features and ponds. The term “Louisiana iris” is a common name that refers to the five different native species naturally found in Louisiana and the hybrids of these species. Louisiana is home to several fantastic iris breeders that have released gorgeous and unique cultivars on the market, and the best time to find Louisiana iris plants at retail garden centers is in the spring — just before and during their blooming season.
For summer we are excited to promote the summer of salvias! We believe the pollinators are excited about this, too. For years we have wanted to include more salvias in the Louisiana Super Plants program, but we could never decide on just one cultivar because there are so many amazing choices on the market! With the need for flexibility, we have decided that we don’t have to limit our choice to a single salvia. Instead, we have recommended a “summer full of salvias.” Additionally, summertime ushers in patriotic feelings for everyone, so we decided to focus on a red, white and blue color palette! We have five cultivars to announce, including:
1) Roman Red — Showy crimson red flowers fully adorn this dense, bushy salvia. Plants have done quite well with average drainage in full sun, and they bring a pop of bright color to the front or middle of the landscape bed.
2) Skyscraper Orange — While technically not red, the dark orange color is a close match, and it is too good to not include! Growing larger than Roman Red with taller flower spikes, this excellent performer stands out at the back of landscape beds and tolerates rainfall and average drainage like a champ. As a bonus, it may perennialize in average to warmer winters!
3) White Flame — White is not a color often associated with salvias, but this amazing new Salvia farinacea shines like a beacon in the landscape. The plants tolerate heat extremely well and may also perennialize in warmer winters, allowing it to bloom earlier in the spring.
4) Mystic Spires Blue (improved) — With its tall spikes of vibrant blue flowers rising above lush foliage, Mystic Spires Blue is one of the showiest salvias on the market. The plants remain compact and bushy, and they tolerate heat and humidity quite well.
5) Rockin’ Blue Suede Shoes — Get ready to rock out all summer long with these fantastic light blue flowers contrasted against dark calyxes. These are big plants, so give them plenty of room! Blue Suede Shoes should easily perennialize in average winters.
Finally, we wanted a plant choice for autumn that perfectly embodies the feeling and colors of the harvest season. And who doesn’t love ornamental peppers? We plant them every year at the Hammond Research Station, and after many years of trying to identify the best, we have decided that this might be an impossible task! Therefore, we are including ornamental peppers as an entire group into the Louisiana Super Plants program. With their tolerance for persistent heat and an eye-catching range of foliage and fruit colors, these plants are the perfect way to both spruce up the late summer landscape and celebrate the transition into fall. While all ornamental pepper cultivars that are found in Louisiana nurseries and garden centers will be considered Louisiana Super Plants, some of our favorites are: Midnight Fire, Black Hawk, Hot Pops Purple, Chilly Chili and Calico. For some added fun, throw in some edible ornamental peppers like Mad Hatter or Candy Cane Red, since peppers labeled solely as “ornamental” are typically not suitable for consumption.
For more information on Louisiana Super Plants, please contact the Hammond Research Station 985-543-4125 or your local LSU AgCenter extension office.
Jeb Fields, Ph.D.
Extension Specialist for Commercial Ornamental Horticulture
Heather Kirk-Ballard, Ph.D.
Consumer Horticulture Specialist
There seems to be a trend in vegetable gardening among homeowners these days. Over and over on social media, in emails and phone calls to the LSU AgCenter, we keep hearing about people not finding success in the vegetable garden. My favorite is the garden meme that says something like “invest $70 into a backyard garden and get a return of $750.” These posts usually evoke responses such as “I only make one or two tomatoes,” or “my bell pepper plants are stunted,” or “that horrible squash vine borer just will not leave us alone!” Someone will comment, “Yeah, right. I invested $2,000 and got 10 really expensive squash and two okra pods.” Sometimes these statements are accompanied by photographs to prove the point of being unsuccessful. Sometimes AgCenter extension agents visit home gardens to see the problem, and sometimes people are simply venting their garden woes online without also indicating what might have gone wrong.
I want Horticulture Hints readers to know that you can be successful in the vegetable garden. Success in the garden, like success in everything in life, comes with a little grit, elbow grease, and the ability to see problems and not run away. Below are a few tips I’d like you to try this summer. These tips will not solve all your problems, but they are a start. Keep letting us, the LSU AgCenter, know what problems you are having (along with a photo or two of the problem) so we can help set you back on the path of success.
Solution: Have you applied fertilizer? Nine times out of 10 the gardener did not incorporate any fertilizer into the soil — or not enough fertilizer. Start with a 13-13-13 fertilizer broadcast into the soil before planting your seeds or seedlings. Let’s just use a medium rate of fertilizer as an example: Use 5 to 6 pounds (10 to 12 cups) of 13-13-13 per 300 square feet. If your garden is only 100 square feet then you would use 2 pounds or 4 cups of 13-13-13. If you have a 4-foot by 8-foot raised bed, that is 32 square feet and you should apply about 1 pound (actually 0.62 of a pound, but round up and make it easy). That would be 2 cups of 13-13-13 before planting. But that isn’t all. You also need to fertilize again when your summer plants begin to bloom. I like 1 tablespoon of calcium nitrate, which is 15% nitrogen, between every other plant. Apply every other week through harvest. You can also use a basic blue water-soluble fertilizer. Those are usually 15% nitrogen as well, and you would apply 1 tablespoon per gallon of water and drench your plants every other week through harvest. This extra bump of nitrogen really increases plant growth and yields.
Solution: Move. Seriously, just get a new house and a new garden. We know it is not practical, but once these moths find you, they have written your address down in their book. So, start by covering your cucurbit plants with insect netting. The netting lets in light but also keeps adults (moths) off your plants. Remove the netting after flowers begin to open. Now you need bees. Otherwise, you will have beautiful plants and vines and no fruit. Next, the moth will come back to find you, so be prepared. Scout your plants three to four times a week. As soon as you see the holes be prepared to mix up an insecticide with the active ingredient bifenthrin. Mix it according to the label. Don’t guess. If you guess then it won’t work for any of us because the larvae will eventually become resistant, and the chemical does not work anymore. Spray the solution right where you see the small hole with “saw dust” coming out of it. That should kill the larvae. You don’t want to use insecticides? Use an X-Acto knife, cut a 1-inch slit parallel with the vine above and below the little hole with sawdust coming out of it. Hand remove the larvae and wrap the vine back together with a small rubber band just tight enough to keep it together without choking off the plant. Also, try not growing any cucurbits for one year. Let the moths go somewhere else and then slowly get back into it.
Solution: Convince your neighbor to grow a vegetable garden and give you the excess. I kid that the only people saving grocery money are those people who live next door to a vegetable gardener. All kidding aside, remember this is a hobby for you. It’s also a form of exercise. Cut the gym membership and buy an extra bag of fertilizer and flat of plants. Well, you say, I still need to go to the gym. I agree. I should be there too. Think of the garden as your own private meditation. Breathe in fresh air. No one is bothering you because the kids think you’re giving yourself a chore. In the crazy busy world we live in, we do not spend enough time outdoors being in nature and watching slow growth and tiny blooms. Turn off your phone, order in dinner — because you know you will be out there until 8:30 p.m. — and think of this as an alternative to therapy. Some reading this article will say, “I don’t need therapy. This is still not saving me money.” Here is my last solution to help you save yourself money in the garden:
|Step 1.||Find a 5-gallon bucket in your shed that has a crack or a broken handle. Do not throw it out.|
|Step 2.||If the crack is not big enough, hit it with a hammer and make it bigger. We need drainage.|
|Step 3.||Fill it with a decent potting soil. Yes, go buy a nice bag of potting soil.|
|Step 4.||Plant three to five cucumber seeds in the bucket. Once they emerge, thin them down to two plants. Or purchase one cucumber seedling and plant it in the middle of the pot.|
|Step 5.||Insert one tomato cage into this 5-gallon bucket.|
|Step 6.||Water each night as you come home from work.|
|Step 7.||When it starts to bloom, give it a little fertilizer, as I mentioned in problem/solution Step 1. You do not need to add any before planting if this is fresh soil with a fertilizer already in it.|
|Step 8.||Email me and tell me how many cucumbers you picked off that single plant this summer.|
You will feel good, I promise! And, just maybe, you will plant a second bucket next year.
Enjoy the Garden,
Kathryn “Kiki” Fontenot, Ph.D.
Vegetable Gardening Specialist
LSU AgCenter School of Plant,
Environmental and Soil Sciences
Summer is the peak growing season for lawns in Louisiana. If you did not fertilize during the spring, you still have time to fertilize and get your yard in good shape prior to fall. Keep up a good fertility program through early to late August. Remember to apply all granular materials on a dry lawn and water very soon after application. Make sure lawns are getting adequate amounts of moisture during the summer months, but don’t overwater. Water deeply only once or twice per week or as needed based on the amount of rainfall. The purpose of irrigation is to supplement rainfall. I am not a fan of watering lawns everyday unless we are in severe drought.
Consider aerifying compacted soil. I’ve seen aerification completely change thin lawns caused by compacted soil into thick and healthy turf. Aerifying helps with water percolation and increases the turf’s rooting depth and makes for a more drought-tolerant lawn. Lawn care companies can aerate, or you can rent an aerator from a rental store and do it yourself. If your soil is prone to compaction, consider aerating one to three times this growing season. Aeration may be the game changer that your lawn is missing.
St. Augustinegrass and zoysia both respond well to fertilizer applications. St. Augustinegrass may be fertilized up to three times during the growing season in April, June and mid-August. Fertilize zoysia twice per growing season in April and again in July.
Bermudagrass is an even bigger fertilizer user and can be fertilized from three to five times during the growing season, especially if you like to mow grass. Carpetgrass and centipedegrass are not big fertilizer users. Up to two applications (in April and an optional application in July) will take care of centipedegrass, and a single application will be sufficient for carpetgrass (April).
Centipedegrass should receive its second and final fertilizer application in July. For centipedegrass, apply only one-half pound of actual nitrogen per 1,000 square feet. For example, apply 3 pounds of 17-0-17 per 1,000 square feet or 5 pounds of 10-0-10 per 1,000 square feet. St. Augustinegrass would need 6 and 10 pounds of the aforementioned fertilizers. If your lawn is not performing well, there could be a nutrient deficiency in the soil. The only surefire way to know what your soil needs is to collect a soil sample and submit it for testing at the LSU AgCenter Soil Testing and Plant Analysis Lab. To simplify the soil sampling and submission process, there are pre-addressed submission boxes with sampling instructions at several garden centers throughout the state and at your local parish extension office. Once submitted, the results will be sent to your home mailbox and or email, usually in less than two weeks. Your parish LSU AgCenter extension agent can help you interpret the results from the soil sample and tell you exactly what’s needed nutrient-wise to make your lawn beautiful.
You may not know this, but there is a correct mowing height for your lawn. St. Augustinegrass is very finicky when it comes to mowing height. Don’t cut it too short and don’t allow it to get too tall. It likes to be maintained around 3 inches, the tallest mowing height of all the lawns grown in Louisiana. If you cut St. Augustinegrass too short, it becomes stressed and more prone to disease and weed infestations.
Centipedegrass is often maintained too tall. Centipedegrass should be mowed to 1 to 1.5 inches. This helps prevent thatch buildup. Zoysia also likes to be mowed in the 1-to-1.5-inch range. Bermudagrass should be mowed from 1 to 2 inches, shorter mowing heights are better when more frequent mowing is possible. Keep mower blades sharp to ensure a clean cut and good lawn health.
Watch for chinch bugs in St. Augustinegrass and bermudagrass lawns and treat with an LSU AgCenter-recommended insecticide such as bifenthrin (Talstar and many other trade names). Chinch bug problems show up as yellowish-brown to straw-colored areas of the lawn during hot, dry weather. These insects extract plant juices from turfgrass stems and crowns while pumping toxic salivary fluids into the lawn. The fluids disrupt the plant’s vascular system. The damage actually resembles herbicide damage. Check for chinch bugs in the lawn by saturating suspected areas with a gallon of water mixed with a few squirts of lemon dishwashing soap. This soapy solution irritates chinch bugs and brings them up near the grass surface so you can see them and determine if the bugs are causing the lawn damage. If it’s hot and dry and there are dead spots in your St. Augustinegrass, chinch bugs are the first thing that I would consider.
Additional insect problems that appear during the summer include armyworms and tropical sod webworms. These moth larvae or “worms” can cause severe lawn damage very quickly and will need to be killed with insecticides to prevent further damage. Tropical sod webworms can devastate St. Augustinegrass and carpetgrass lawns. Tropical sod webworms crushed St. Augustinegrass in 2020. However, populations were not severe in the 2021 growing season. Armyworms prefer bermudagrass and can completely defoliate acres of pasture and lawns. Carbaryl, bifenthrin and chlorantraniliprole insecticides are options for tropical sod webworms, armyworms, as well as chinch bugs infesting the lawn.
Be mindful of these pests as you walk through your lawn. Investigate damaged areas and treat accordingly.
In late spring to early summer, Virginia buttonweed starts forming mats that can eventually smother out the lawn. Pull up small populations of Virginia buttonweed or carefully treat with herbicides like metsulfuron (MSM Turf and other trade names) or Celsius. These herbicides work well with repeated applications spaced four to six weeks apart. Metsulfuron and Celsius can be safely applied on St. Augustinegrass, centipedegrass, bermudagrass and zoysia during warm weather. Carpetgrass will be damaged by the herbicide Celsius. Bahiagrass will not tolerate metsulfuron or Celsius. When it comes to “managing” buttonweed it is important to start spraying early in the growing season (April) and spray often. Don’t wait until September to make your first herbicide application.
Common lespedeza is a mat-forming annual legume that emerges in the spring and lingers deep into fall throughout Louisiana. By late summer, the plant matures and becomes woody-like and tough on lawnmower blades. Metsulfuron works well on this weed, but early summer applications are more effective.
Torpedograss is a perennial grass that’s mainly a problem in south Louisiana, but I do get calls about it from north Louisiana as well. There are few lawn problems more devastating than a torpedograss infestation. Torpedograss is extremely tolerant of herbicides and easily outcompetes slow-growing grasses like centipedegrass.
The weed often starts from soil brought in during flower bed construction. However, it quickly spreads from the flower bed to the lawn. The ability to suppress torpedograss in lawns depends on the turfgrass species. Selectively removing torpedograss out of lawn grasses and sports fields is rarely completely achievable. Quinclorac (Drive and other trade names) is an herbicide that is somewhat effective in suppressing torpedograss in bermudagrass and zoysia. Unfortunately, you cannot use quinclorac in centipedegrass and St. Augustinegrass.
Sethoxydim (Bonide Grass Beater and other trade names) will temporarily injure torpedograss infesting centipedegrass, but it does not provide long-term control. The torpedograss recovers and the weed re-infests the centipedegrass. Unfortunately, there are no selective herbicide options for torpedograss infesting St. Augustinegrass. Often, complete renovation is necessary when centipedegrass and St. Augustinegrass are severely infested.
If you decide to renovate and install a new lawn, consider sodding the lawn with zoysia (semi-shady or full sun lawns) or bermudagrass (for full sun only). Converting to zoysiagrass or bermudagrass will allow the use of quinclorac, the most effective selective herbicide on torpedograss. Installing zoysia may be the better fit for Louisiana because of its good shade tolerance and drought tolerance. Zoysia is not a high maintenance grass when managed properly. Maintain zoysia at 1 to 1.5 inches with a sharp mower blade and fertilize twice per year. There are several sod farmers in Louisiana that grow zoysia, so it is readily available.
Proper lawn maintenance keeps your lawn healthy and reduces the need for the use of pesticides. If it becomes necessary to use a pesticide in the lawn, it is highly important to always read and follow their labels before using. The label will tell you how to use the product safely to achieve satisfactory results. You will find the label attached to the product’s container.
Ron Strahan, Ph.D.
Weed Scientist and Turfgrass Specialist
A new disease, Pestalotia leaf spot and fruit rot, which is caused by the fungus Neopestalotiopsis species, has been detected in strawberries in Louisiana. An aggressive form of this pathogen was first detected in Florida during the 2018-19 growing season. The disease has since been confirmed in Georgia, North Carolina and Texas. More recently, the pathogen has been detected in strawberry fields in south Alabama.
Initially, the pathogen causes leaf spot and fruit rot but later infects crowns and roots, leading to plant death. Leaf spots vary in size and are light to dark brown with tan centers. Similar spots appear on the fruits, but these spots are slightly sunken and cause rotting of fruits. As the disease progresses, tiny black fungal fruiting bodies appear on both leaf and fruit spots. These fruiting bodies produce spores under favorable environmental conditions. The disease favors extended rainy weather, and disease development is optimal between 77 to 86 degrees F.
The disease spreads to new strawberry fields by means of infected transplants. Once introduced, the pathogen spreads within a field or to nearby fields by rain splashes and irrigation water, contaminated field equipment, and field workers. Successful disease management requires integrating cultural and chemical control practices. Growers must buy disease-free, healthy transplants to avoid introduction of the pathogen to new fields. Careful inspection of transplants is necessary, as initial disease symptoms may not be readily visible. Sanitation of farm equipment is helpful in reducing local disease spread within and to nearby fields. Farm workers should limit field activities when plants are wet.
The leaf spots and fruit rot caused by Neopestalotiopsis species can be easily confused with other strawberry diseases; therefore, accurate diagnosis and identification is required. If you suspect this new disease in your strawberries, please contact your local parish agent. The LSU AgCenter Plant Diagnostic Center is available for your plant diagnostic needs. If you need more information regarding sample submission, please call 225-578-4562 or visit our website at www.lsuagcenter.com/plantdiagnostics.
Raj Singh, Ph.D.
Director, LSU AgCenter Plant Diagnostic Center