Curative and eradicant action of fungicides to control Phakopsora pachyrhizi in soybean plants

In experiments conducted in a growth chamber and in laboratory, the preventive, curative and eradicative action of fungicides was assessed for the control of Puccinia triticina races MFT-MT and TFP-HT. The effect of fungicides tebuconazole (triazole) and azoxystrobin (strobilurin) was evaluated separately. Seedlings were inoculated with a suspension of 50 x 103 uredospores/mL distilled water added of 120 μL adjuvant (polyoxyethylene sorbitan monolaurate Tween 20 - Synth). Fungicides were applied 24 hours before inoculation (preventive control), 96 hours after inoculation (curative control) and ten days after inoculation (eradicative control), both in seedlings (in vivo) grown in pots and in leaf segments (in vitro) on Petri dishes. The effect of treatments based on the number of uredia/cm2 and the production of uredospores/uredium were tested in vivo and in vitro. When applied preventively, for both races, the two fungicides controlled 100% leaf rust, and when applied curatively, only azoxystrobin led to 100% control. The tested races remain sensitive to azoxystrobin but maintain the reduction in sensitivity to tebuconazole. Detached wheat leaf assay was efficient in assessing the sensitivity of P. triticina races to fungicides and leaves remained green for 18 days.

show abstract

“…Penetrating fungicides that are absorbed by the leaves have protective, curative and eradicative actions (7,14).…”

Section: Resultsmentioning

confidence: 99%

Detached wheat leaf assay for assessing the sensitivity of Puccinia triticina races to fungicides

Turra

Reis

Barcellos³

2017

Summa phytopathol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…In these situations, directional selection occurs where some site-specific fungicides become less efficient season-after-season. However, the penetrating-mobile fungicides before the sensitivity reduction has been detected they had a protective, curative, and eradicating action in the ASR control (Godoy & Canteri, 2004;Reis & Zanatta, 2016).…”

Section: Directional Selection × Preventive Curative and Eradicant Sprayingsmentioning

confidence: 99%

Directional Selection of Phakopsora pachyrhizi Towards Site-Specific Fungicides in Mato Grosso State

Reis¹,

Zambolin²,

Guerra³

2021

JAS

Self Cite

View full text Add to dashboard Cite

This review focus on the sensitivity reduction of Phakopsora pachyrhizi to site specific fungicides in the Brazilian state of Mato Grosso.The soybean grown area in this state in the 2018/19 growing season was 9,756,668 hectares. The main crop disease is Asian soybean rust that depending on disease severity may cause 80% yield reduction. The rust chemical control started in the 2002/003 season with site-specific fungicides applied solo and with 3.6 sprayings/ha/season. For these reasons, the fungus had sensitivity reduction to the fungicides DMIs, QoIs and SDHIs resulting in a short effective life. Anti-resistance strategies were not adopted to prevent or delay the development of soybean rust resistant population to site-specific fungicides. Reduced sensitivity to the target site has been observed for all site-specific fungicides involving cross and multiple resistance resulting in ineffective control. So far, eight mutations in Phakopsora pachyrhizi have been identified conferring reduced sensitivity to DMIs, QoIs and SDHIs but so far specific mutations are not considered in chemical control. The directional selection has occurred and has been aggravated season-after-season by the continuous use of site-specific fungicides in a large area, for 18 season and with more than three sprayings/area/season. The presence of soybean weed in one million hectares of cotton crop infected by rust aggravates the directional selection. Anti-resistance strategies should include sowing at the beginning of the recommended season, avoid the December season and replacing it by February, use of scientific criteria to time the first application and the use of multisite fungicides in all applications and in the entire area cultivated with soybean.

show abstract

“…(3) Preventive application, although all mobile penetrating fungicides have preventive, curative and eradicative action (Godoy & Canteri, 2004;Reis & Zanatta, 2016);…”

Section: Final Remarksmentioning

confidence: 99%

An Overview of the Epidemiology of Phakopsora pachyrhizi in the State of Mato Grosso, Brazil

Reis¹,

Guerra²,

Zanatta³

et al. 2021

JAS

Self Cite

View full text Add to dashboard Cite

This review seeks to expand the knowledge about the epidemiology of Asian sybean rust in the state of Mato Grosso and contribute to ensuring the economic sustainability of soybean crop. It is discussed the Phakopsora pachyrhizi potential of dispersal from Asia to South America and finally to Mato Grosso state. The origin of the Asian soybean rust inoculum within Mato Grosso is addressed by the survival in volunteer and soybean weed plants (Pitelli, 2015) in other crops such as cotton. Data on the adverse environmental effect on the soybean plants survival are shown mainly the water deficit from June to August. Reports on the effect air temperature and mainly solar radiation on the mortality of airborne spores during their anemophilous spread on sunny days are also discussed. This increase of knowledge aims to make the soybean-free period more efficient by the knowledge on the soybean plants survival and on the fungus viability in the month of August. Due to the proximity of soybean farms, during the soybean-free period, in other states (Tocantins, Goiás, Rondônia, etc.) and in other neighbor countries we discuss the likelihood that inoculum in the state may also originate in out-of-state crops during the Mato Grosso soybean-free period.

show abstract

Curative and eradicant action of fungicides to control Phakopsora pachyrhizi in soybean plants

Cited by 6 publications

References 10 publications

Detached wheat leaf assay for assessing the sensitivity of Puccinia triticina races to fungicides

Detached wheat leaf assay for assessing the sensitivity of Puccinia triticina races to fungicides

Directional Selection of Phakopsora pachyrhizi Towards Site-Specific Fungicides in Mato Grosso State

An Overview of the Epidemiology of Phakopsora pachyrhizi in the State of Mato Grosso, Brazil

Contact Info

Product

Resources

About