Degree days. Phytosanitary treatments

Crop protection treatments can follow schedules based on degree days; there are different studies for different needs that indicate this.

For example, sports surfaces consisting of Festuca Arundinacea often have weed problems, especially Paspalum Dilatatum, "Dallisgrass". Due to current restrictions on the use of the herbicide MSMA, other herbicides such as Fluazifop-p-butyl, mesotrione or a mixture of both are being used. Recommendations with superior success to 90% are given by trials conducted at the University of Tennessee by Matthew Elmore and James Brosnan, 2008, with applications of fluazifop-p-butyl (0.28 kg/ha) and fluazifop-p-butyl (0.28 kg/ha) mixed with mesotrione (0.105 kg/ha) with a first application in early spring (< 160 degree day, with a base temperature of 10°C) and repeated applications, spaced 3 weeks apart.

Predictive methods based on the climatic data of each area can be carried out in order to approximate curves showing the degree days on the one hand and the germination percentage of certain weeds on the other. In this way it is possible to carry out preventive treatments after estimating the germination date.

Studies carried out over a period of 3 years, M.A. Fidanza, 1998, revealed that the first germinations of Digitaria spp, "Crabgrass", took place when the soil temperature was above 12º C, with maximums occurring at soil temperatures above 20º C and a cumulative 185º F degree day.

We can also follow different treatment models proposed based on studies of degree days by different authors:

Objective Description Reference

Poa annua Flowering Danneberger and Vargas, 1984

Poa annua Periods of stress Danneberger and Street, 1985

Poa pratensis Root growth Koski, Street and Danneberger, 1988

Digitaria Germination Fidanza, Dernoeden and Zhang, 1996

Festuca arundinacea Flowering DiPaola, Lewis and Gilbert, 1987

Anthracnose Occurrence Danneberger, Vargas and Jones, 1984

Rizoctonia " Shumann, Clarke, Rowley and Burpee, 1994

Sclerotinia " Hall, 1984. Canadian J. Soil Science

Pythium " Nutter, Cole and Schein, 1983

• adapted from Danneberger, T.K. 1993. Turfgrass ecology and management.