Winter Wheat Cultivar Responses to Fungicide Application are Affected by Nitrogen Fertilization Rate

Abstract

Foliar fungicides are important management inputs for winter wheat (Triticum aestivum L.) in high-yielding areas of Europe, but their effectiveness may interact with cultivar selection and nitrogen (N) fertilization. No information is available on the potential use of fungicides in reducing yield losses from foliar diseases in Croatia, where wheat crop is extensively grown under low N inputs. Field experiments were conducted during 2000-02 to evaluate the agronomic responses of six winter wheat cultivars to fungicide application (tebuconazol around heading) compared with untreated plots at low (67 kg N ha )1 ) and high (194 kg N ha )1 ) N fertilization rates. Grain yields tended to increase in all years following fungicide treatment at high N rate by an average of 10.1 % (773 kg ha )1 ), but improved significantly in one year only at low N rate. When these occurred, yield increases were associated with larger grain weight per ear primarily due to heavier 1000-kernel weight. Cultivars differed in their responses to fungicide application across growing seasons and N fertilization rates. Under low disease pressure in 2000 and 2001, improved yields with fungicide use occurred for few susceptible cultivars only, whereas all cultivars significantly increased yields under higher disease severity in 2002 by an average of 383 kg ha )1 (5.0 %) at low N rate and 1443 kg ha )1 (19.0 %) at high N rate. Following fungicide application at high N rate, some susceptible cultivars outyielded resistant cultivars, whereas opposite responses occurred in untreated plots. High N fertilization rate consistently produced larger grain yields except under high disease severity and no fungicide sprayed in 2002, when it had no benefits at all over low N rate. Fungicide application showed limited importance for wheat performance at low N rate; however, cultivars significantly differed in yield responses as well as in rankings after fungicide use at high N fertilization rate.

Wheat powdery mildew and foliar N concentrations as influenced by N fertilization and belowground interactions with intercropped faba bean

“…Some studies have demonstrated a significant influence of N fertilizer on powdery mildew, with a strong positive correlation between N rate and severity index of the disease and a significant negative correlation between grain yield and disease index (Zhang and Zhang 1991;Gao et al 1993). Wheat grain yield and product quality were found to be substantially influenced by N nutrition (Guttieri et al 2005;Varga et al 2005) and foliar disease (Puppala et al 1998), and N utilization and management are recognized as very important factors in wheat production (Olesen et al 2000;Kratochvil et al 2005). Numerous studies have indicated the advantageous effects of various cultural practices on disease control and higher yields, including mixtures of several varieties (Mundt 2002;Cox et al 2004) or intercropping wheat with other species (Trenbath 1993;Zhu et al 2004) and N fertilizer utilization associated with fungicide application (Varga et al 2005).…”

Assessment of Wheat Foliar Mycofloraand Its Management Strategies in District Bhimber, Azad Kashmir, Pakistan

“…In this research, five different fungicides were used as chemical treatment on wheat leaves at appearance of fungal disease symptoms. Spray of fungicides reduced fungal infections especially and improved wheat yields (Varga et al, 2005;Carmona et al, 1999).…”

Recent Advances on Integrated Foliar Disease Management with Special Emphasis in Argentina Wheat Production

“…Increased yields disease management are associated mainly with an increase in thousand grain weight [72,73,78,79,80], while other yield components such as number of spikes.m -2 [72] or grains.spike -1 [72,79,80,81] are usually not affected by disease severity. However, Simón et al [82] reported that preventing early wheat infection by Septoria tritici could result in an increase of spikes.m -2 and grains.spike -1 .…”

“…Management practices such as N fertilization can also affect the expression of wheat foliar diseases [82,84] and the effectiveness of foliar fungicide application [72,82,84,85]. Increasing N rates may cause negative, positive or neutral effect on foliar disease severity, depending on the geographic location [86] and the type of disease.…”

“…The response to fungicide application depends on the severity of specific foliar diseases, cultivar disease resistance or tolerance, management practices, and environmental conditions [71,72,73]. Fungicides applied at flag leaf and spike emergence of winter wheat increased mean grain weight and grain yield when they extended canopy life [74].…”