LSU AgCenter Horticulturist
(09/25/20) The weather is cooling, and the days are getting shorter. We’re now into astronomical fall following the autumnal equinox. There are so many things we can do in the garden this time of year. Fall is a great time to work in the landscape.
Many tasks can be done in preparation for winter. And the cooler weather it makes it so much more delightful.
Take care of weeds in your flower beds and vegetable gardens. Apply a thick layer of mulch about 2 to 3 inches deep with pine straw, leaves, straw or bark to help protect the roots of citrus trees and shallow-rooted trees and shrubs such as camellias from cold snaps in the coming months leading up to winter.
The lawn may be giving you fits right now. Virginia buttonweed and common lespedeza are major weed problems this time of year. They can be controlled with herbicides that contain the active ingredient metsulfuron such as MSM Turf or Celsius if the temperatures are over 85 degrees.
Once weeds have flowered they are more difficult to control. You may need to apply herbicides more than once to control them. As the weather cools you can begin using herbicides with the active ingredient atrazine in combination with 2, 4-D + mecoprop + dicamba + carfentrazone for the best results. Follow the product label for rates, and use a spreader sticker to improve coverage.
Stop applying nitrogen-containing fertilizers to your lawn now as the high nitrogen promotes fungal diseases such as large patch and grey leaf spot that are common in the fall. Fungal diseases appear as large circles in the grass that begin as yellowing leaves that transition to brown as the grass dies.
Control these fungal diseases with a granular fungicide containing one or more of the following ingredients: maneb, myclobutanil, PCNB, propiconazole, thiophanate-methyl and triadimefon. Be sure to follow label instructions.
Be careful not to confuse fungal disease with damage from insects such as sod webworms, armyworms or chinch bugs. They can also be a major problem this time of year as well, and sod webworms have definitely been an issue this year.
Check for caterpillars and chew marks on grass to confirm sod webworm presence. The moths in the grass are a dead giveaway for webworms and armyworms. Use an insecticide with the active ingredient bifenthrin for control. Treat again in seven days to take care of newly hatched eggs.
If you’ve got plants you want to add to your landscape, now is a great time to do so as the weather cools and water demands have decreased. Consider selecting trees that have good fall foliage color change for added beauty. Some great trees with beautiful fall foliage colors are bald cypress, black gum, Chinese pistache, dogwood, hickory, Japanese maple, oaks of many kinds, red swamp maple, southern sugar maple, sweet gum and sycamores.
October is traditionally the driest month of the year in Louisiana. Make sure trees and shrubs are receiving enough water so that they do not become stressed and more susceptible to disease and insects.
This is also a good time to address other insect problems such as scales. Use a horticultural oil spray to help control scale on camellias, magnolias, gardenias and citrus. This will also help control whiteflies.
Purchase and plant strawberry plants in October. Some recommended varieties are Sea Scape, Camarosa, Eversweet and Chandler. Fertilize them with one-third pound of 10-10-10 per 100 feet of row.
In the vegetable garden, plant cool-season vegetables such as leafy greens in addition to broccoli, cabbage and cauliflower. Control caterpillars on your cool-season vegetables with Bacillus thuringiensis (Bt) insecticide. This is considered an organic insecticide safe for use in vegetable gardens.
For me, the changing of the seasons always sparks an itch to decorate. In the fall, we think of Halloween, All Saints Day and Thanksgiving. The fall ushers in thoughts of harvesttime and the changing colors of the leaves. Orange is the official color of fall (well, in my book anyway). You can use many different types of flowering plants to incorporate not only orange but also yellow and red, the other traditional colors of the changing leaves.
The most common flowers of fall, of course, are mums. For decorations, you also can incorporate bales of hay or straw in addition to corn stalks and pumpkins that are easily found at most local retail nurseries as well as large chain stores and even grocery stores.
Pumpkins are a true symbol of the fall. There are many varieties in many colors these days to choose from. Make your pumpkins last longer by wiping the outside of them with a 10% bleach solution to kill any fungus or bacteria, thereby preserving and extending their life.
Once carved, you can dip your jack-o-lanterns into a bucket of 10% bleach solution again. Make them last longer by applying Vaseline, vegetable oil or WD-40 for moisture retention after cleaning with the bleach solution, or keep pumpkins refrigerated. Do not use real votive candles; use battery-operated votives instead.
You can also use acrylic paints or washable paints and skip the carving all together. This can be a fun and creative way to decorate pumpkins for the whole family. Try planting your own pumpkins next summer in July.
Garden mums do best in full to partial sun in a well-drained but moist soil.Photo by Sara Shields/LSU AgCenter
Pumpkins, gourds and squash are fall vegetables that also are used to make holiday decorations. LSU AgCenter file photo by Allen Owings
Chinese pistache is adapted to Louisiana and provides brilliant fall color. Photo by Heather Kirk-Ballard/LSU AgCenter