Management of Pyrenophora teres f. teres, the Causal Agent of Net Form Net Blotch of Barley, in A Two-Year Field Experiment in Central Italy

Abstract

Pyrenophora teres is the causal agent of barley net blotch (NB), a disease that can be found in two different forms: net form (NFNB), caused by P. teres f. teres, and spot form (SFNB), caused by P. teres f. maculata. A two-year field experiment was carried out to evaluate the response to NB of six different barley cultivars for malt or feed/food production. In addition, the efficacy of several recently developed foliar fungicides with different modes of action (SDHI, DMI, and QoI) towards the disease was examined. After NB leaf symptom evaluation, the identification of P. teres forms was performed. Grain yield was determined, and pathogen biomass was quantified in the grain by qPCR. In the two experimental years characterized by different climatic conditions, only P. teres f. teres was detected. The tested cultivars showed different levels of NFNB susceptibility. In particular, the two-row cultivars for malt production showed the highest disease incidence. All applied fungicides exhibited a high efficacy in reducing disease symptoms on leaves and pathogen accumulation in grains. In fact, high levels of fungal biomass were detected only in the grain of the untreated malting barley cultivars. For some cultivars, grain yield was positively influenced by the application of fungicides.

The Combination of Low-Cost, Red–Green–Blue (RGB) Image Analysis and Machine Learning to Screen for Barley Plant Resistance to Net Blotch

“…f. teres and the spot form of NB caused by P teres. f. maculata [13]. Both forms of this fungal pathogen will decrease grain yield and quality, ultimately contributing to noticeable economic losses.…”

“…To date, resistance to the net form of NB has only been witnessed in a limited number of cultivars, while the majority of cultivars display only minimal susceptibility to the spot form of NB; this can greatly complicate the identification of resistant lines [13,[19][20][21]. An additional challenge is that the evaluation of net blotch lesion severity traditionally involves visual assessments which employ a standardized 1-10 scale and are conducted as the disease progresses [22].…”

SDHI resistance in Pyrenophora teres f teres and molecular detection of novel double mutations in sdh genes conferring high resistance

“…In NB, foliar application of fungicides should be recommended when the disease reaches an economic level of damage or when the alarm threshold justifies the chemical control 16,20,21 . Currently, the fungicidal active ingredients (a.i.)…”

“…10,16 In NB, foliar application of fungicides should be recommended when the disease reaches an economic level of damage or when the alarm threshold justifies the chemical control. 16,20,21 Currently, the fungicidal active ingredients (a.i.) in use in Argentina for the chemical management of foliar barley diseases include mixtures of quinone outside inhibitors (QoI) (chemically strobilurins), demethylation inhibitors (DMI) (chemically triazoles) and SDHI (chemically carboxamides).…”

Net blotch of barley (Hordeum vulgare), caused by Drechslera teres and its effect on yield

“…Drechslera teres es un parásito necrotrófico capaz de extraer sus nutrientes de tejidos muertos y de restos de cultivos y es transmitido en las semillas con una tasa del 21 % (Carmona et al, 2008). El monocultivo de cebada, la siembra en directo y el uso de semillas infectadas con el patógeno, propician un patosistema ideal para el desarrollo de la enfermedad (Abebe, 2021;Hampton, 1980;Jordan, 1981;Piening, 1968;Pierre et al, 2010;Tini et al, 2022).…”