Wednesday, January 26, 2011

Weed Control in Established Turf - Preemergence Weed Control

Mid-February is a good time to start controlling crabgrass in your lawn

In established turfgrass, members of the dinitroaniline herbicide family ( e.g., oryzalin [Surflan], benefin [Balan], prodiamine [Barricade], or pendimethalin [Pendulum, Pre-M]) provide control of annual grass and some broadleaf weed species when applied prior to weed seed germination.

Oxadiazon (Ronstar), bunsulide (Betasan, Pre-San) and dithiopyr (Dimension) also provide preemergence annual grass and broadleaf control.

Atrazine and isoxaben (Gallery) provide preemergence control of primarily broadleaf weeds.  More more details refer to EDIS Publications EP141 (

Caution:  Some so called "Southern Lawn Weed Control" products cannot be used on Floratam St. Augustine lawns without causing harm.  Read and follow all label directions for your safety and the safety of your enviornment.

Friday, January 21, 2011

Winter is Still Here

The National Weather Service predicts a possible freeze the south Florida vegetable farms next week.  The local news broadcasts indicated mid-30's early next week.  Some of the tropical plants should be looked over to see if there is anything worth saving from the previous freeze days we have experienced this year.  If there is still hope, then get the covers out.  Remember to cover the plants all the way to the ground to trap heat leaving the soil.  Wrapping the tops only will not protect the plant (looks like a lollipop before the wrapper is removed).

The real-time, local weather can be observed by going to the Florida Automated Weather Network (FAWN) at .  This is the Apopka site at the Mid-Florida Research and Education Center.  It is not a predictive tool, but a real-time view that is updated every 15 minutes.

Stay warm; spring is not too far off.

Thursday, January 13, 2011

Protecting Plants from Freeze Damage - Understanding Irrigation for Freeze Protection

What the Public Needs to know about Protecting Strawberries from Freeze Damage by Craig Chandler and Vance Whitaker (Gulf Coast Research and Education Center -

(Although this article speaks about strawberry freeze protection specifically, the information is appropriate for any fruit, vegetable or ornamental plant in the garden or landscape.)

As you talk to people about strawberry freeze protection, here are some facts you may want to keep in mind:

Understanding that this was an extremely rare January (2010) can be of great help to the public. Typically, there are no more than a few freezes each winter in the Plant City/Dover area (Hillsborough County – Central Florida – USDA Hardiness Zone 9b), and these are often of short duration (3-4 hours or less). A period of 9 days in which the minimum daily air temperature is below 32 ° F and the maximum air temperature is ≤ 60 °F, as was the case during the first half of January this year, is a once in a lifetime occurrence. According to FAWN (Florida Automated Weather Network – ), the weather station at Dover typically experiences a total of 96 hours below 45 °F in January. This year (2010) it was 264 hours.

When a freeze is the result of clear skies and calm conditions, sprinkler irrigation is an efficient and cost effective method to protect strawberry flowers and fruit (in a commercial setting). Eighty calories of energy (in the form of heat) are generated for each gram of water that freezes. This heat can keep plants at 32 °F, but water has to be applied continuously and in sufficient quantities.

Newspaper and TV reporters often state that a coating or blanket of ice insulates flowers and fruit, protecting them from air temperatures below 32 °F.  To the casual viewer or reader this sounds like a logical explanation, but if it were true, sprinkler systems could just be run until the plants were covered with ice and then turned off. What protects strawberry flowers and fruit is the heat of the liquid water (which comes out of the ground at about 72 °F) and the heat that is generated as the irrigation water changes from liquid to solid (a chemical property known as the heat of fusion).

Damage to strawberry flowers and fruit can start to occur when tissue temperature reaches 30 °F. A period of very warm weather preceding the freeze may result in tissue being damaged at a higher temperature. Conversely, a period of cold weather preceding the freeze may condition tissue such that it can withstand temperatures below 30 °F before damage occurs.

When there is little or no wind, sprinkler systems will generally not be turned on until the air temperature is 31 °F. However, when an advective (windy) freeze is expected, it is common to turn the sprinkler system on when the air temperature is 34 °F. This is because the temperature of wet plant tissue exposed to wind will initially drop due to evaporative cooling. Then as water begins to freeze, the heat of fusion will counteract the heat loss due to evaporation and the temperature will stabilize at about 32 °F.

Wind can result in evaporative cooling that lowers tissue temperatures 5-6 °F below the air temperature. This is why, if it’s windy, the air temperature may need to be 36 °F or higher before it is safe to turn off the sprinklers.

Friday, January 7, 2011

Vegetable Gardening Question - 2011

I want to start my spring vegetables from seed however, I just don't know when to start. I want to plant all of the regular spring/summer vegetables (Tomatoes, cucumbers, beans, peppers, squash, eggplant, watermelon etc.) When do I start these seeds indoors to get a head start?  What vegetables are worth growing from seed and which are best to just buy seedlings (transplants)?

If it will fit into your schedule, I recommend you attend the upcoming Vegetable Gardening class on January 15th at 9:00AM.  Call our Master Gardener Clinic to register for the class at (407) 254-9200.

Next week is a good time to start your seedlings for the Warm Season garden.  They will need 4-6 weeks before you plant them out in the garden in late February or early March.  Tomatoes, Peppers, Eggplants are ideally started as seedlings for use as transplants in the garden.  Squash, Melons, Beans and Cucumbers should be planted in the ground during the first week of March.  These vegetables planted in March will reach maturity by June.  Summer vegetables include sweet potatoes, okra, cherry tomatoes, and southern peas.  Otherwise, summer is not a good time of year to grow your vegetables in Central Florida.

Read a copy of the Florida Vegetable Gardening Guide with Orange County planting tables:   Pages 10-12 of the guide lists varieties that grow well in Florida.  Use fresh seeds from the local garden center (or purchase on-line).  Look over the planting table and you can see which vegetables can be grown as transplants and those that should be directly sown in the ground.

Tuesday, January 4, 2011

A Resource for Pests and Diseases of Cultivated Palms - Symptoms of Diseases and Disorders

Dr. Monica Elliott has a new tool to help us evaluate Pests and Diseases of Cultivated Palms. She says it is "another set of tools to help with palm problem diagnosis". There are several hyperlinks on the webpage. The first link is for palm symptoms, including insect damage (the insect is gone, but the damage is left behind). The second link is a basic identification tool for arthropod pests of palms. The third link is for the entire resource. She also says "more tools in the resource are forthcoming by UF-IFAS and DPI staff that will deal with precise insect and mite identification and palm species identification". Visit this link: