Timing of Preemergent (PRE) Herbicide Applications for 2023 – Apply Earlier – Like Now!!!

Posted On January 11, 2021— Written By
en Español / em Português
Español

El inglés es el idioma de control de esta página. En la medida en que haya algún conflicto entre la traducción al inglés y la traducción, el inglés prevalece.

Al hacer clic en el enlace de traducción se activa un servicio de traducción gratuito para convertir la página al español. Al igual que con cualquier traducción por Internet, la conversión no es sensible al contexto y puede que no traduzca el texto en su significado original. NC State Extension no garantiza la exactitud del texto traducido. Por favor, tenga en cuenta que algunas aplicaciones y/o servicios pueden no funcionar como se espera cuando se traducen.


Português

Inglês é o idioma de controle desta página. Na medida que haja algum conflito entre o texto original em Inglês e a tradução, o Inglês prevalece.

Ao clicar no link de tradução, um serviço gratuito de tradução será ativado para converter a página para o Português. Como em qualquer tradução pela internet, a conversão não é sensivel ao contexto e pode não ocorrer a tradução para o significado orginal. O serviço de Extensão da Carolina do Norte (NC State Extension) não garante a exatidão do texto traduzido. Por favor, observe que algumas funções ou serviços podem não funcionar como esperado após a tradução.


English

English is the controlling language of this page. To the extent there is any conflict between the English text and the translation, English controls.

Clicking on the translation link activates a free translation service to convert the page to Spanish. As with any Internet translation, the conversion is not context-sensitive and may not translate the text to its original meaning. NC State Extension does not guarantee the accuracy of the translated text. Please note that some applications and/or services may not function as expected when translated.

Collapse ▲

From previous research, we know that crabgrass germinates with 24-hour mean soil temperatures average about 53-55 degrees at a 2 to 4 inch depth for several consecutive days. Because the climate in NC is quite varied (ski resorts in western NC and palm trees in eastern NC), the actual date of the critical soil temperature varies significantly. Traditionally, in the southeastern part of the state, we know that PRE herbicides should be applied and watered in by about March 1, in the Piedmont about March 15, and in western NC about early April (depending on the elevation). Based on observations of crabgrass emergence and data from NOAA (National Oceanic and Atmospheric Association), my recommendation for 2023 is for turfgrass managers to apply PRE herbicides at least two weeks earlier than previous recommendations.

Why the change? In 3 of the last 4 years, I have found crabgrass emergence in late February (see photo). In the previous 30 years of my career, I have never seen crabgrass emergence in February. January of 2023 was the third warmest ever recorded in NC. The average soil temperature at our Turf Field Lab in Raleigh averaged 51 degrees for the month of January. The bottom line is, apply your PRE herbicides now.

Is there a penalty for applying PRE herbicides too early? The answer is:  not much. PRE herbicides are degraded (primarily) by soil microorganisms. When soil temperatures are in the 40s and 50s, microorganism activity in soil is low. Therefore, minimum degradation of PRE herbicides occur when applied in January and February. Crabgrass germination in late February