نتایج جستجو برای: and therefore decreasing pest population density in crop season

تعداد نتایج: 21803201  

A. Shekoofa Y. Emam

The aim of the present investigation was to study the growth, yield and yield components of maize (Zea mays L.) single cross 704 under different levels of irrigation, plant density, and ethephon in southern Iran where this particular crop has not yet been studied in detail. A field experiment was performed in the 2004 5 growing season at the experimental farm of the College of Agriculture, Shir...

پایان نامه :0 1375

the following null hypothesis was proposed: there is no significant difference between the efl students listening comprehension development receiving pictorial cues and those receiving no cuse. to test the null hypothesis, 52 male and femal freshmen students of medicine studing at iran university of medical scinces were randomly selected from a total population of 72 students. to ensure that th...

2010
Adrien Rusch Muriel Valantin-Morison Jean-Pierre Sarthou

There is a growing body of evidence to suggest that the simplification of land uses associated with a strong dependence on agrochemical inputs is decreasing environmental quality, threatening biodiversity, and increasing the likelihood of pest outbreaks. The development of farming systems with greater reliance on ecosystem services, such as biological control of insect pests, should increase th...

2012
Raymond A. Cloyd

Pesticides including insecticides and miticides are primarily used to regulate arthropod (insect and mite) pest populations in agricultural and horticultural crop production systems. However, continual reliance on pesticides may eventually result in a number of potential ecological problems including resistance, secondary pest outbreaks, and/or target pest resurgence [1,2]. Therefore, implement...

Journal: :Physics of life reviews 2014
Sergei Petrovskii Natalia Petrovskaya Daniel Bearup

Pest insects pose a significant threat to food production worldwide resulting in annual losses worth hundreds of billions of dollars. Pest control attempts to prevent pest outbreaks that could otherwise destroy a sward. It is good practice in integrated pest management to recommend control actions (usually pesticides application) only when the pest density exceeds a certain threshold. Accurate ...

2009
Jon M. Conrad

This paper applies option value theory to determine the timing and value of pesticides in controlling crop damage. Entomologists and economists have both sought to determine '~ction" or 'economic" thresholds which would trigger the application of a pesticide, or an alternative pest control policy. These concepts are reviewed, and the differences arising in each discipline are noted. Two mathema...

2008
Kent M. Daane

economi(about 15%) ) was rarely ­ mechacally important and the ­ nisms leading to reduction were not clear. For example, l , there numwere few differences f in the ­ berr off leafhopperr predators or parasitoids on i the vines in cover cropped versus no coverr sigplots. However, r, there were ­ differnificant between-treatment ­ ences in vine growth. Plots with seasonwide maintenance off a cove...

2017
Justin Clements Sean Schoville Nathan Clements Scott Chapman Russell L Groves

BACKGROUND The Colorado potato beetle, Leptinotarsa decemlineata (Say), is a major agricultural pest of commercial potatoes. Pest managers use a combination of control tactics to limit populations, including multiple insecticides. Finding a window of insecticide susceptibility and understanding genetic responses to insecticide exposure during a growing season may provide novel management recomm...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی اصفهان - دانشکده شیمی 1389

in this thesis, phosphorus ylides [phbppy], [no2bppy] and [brbppy] have been synthesized through the formation of phosphonium salt and dihydrogenation, followed by the reaction of pd(oac)2 and the orthopalladated dinuclear complexes [pd(?-cl)(phbppy)]2, [pd(?-cl)(no2bppy)]2 and [pd(?-cl)(brbppy)]2 have been produced. the reaction of dinuclear complexes and bidentate ligands [l = bipy (2,2-bipyr...

A. R. Sepaskhah A. Shabani

H Harvest index (HI), ratio of seed yield to aboveground dry matter, is a very important parameter for estimating seed yield in several crop models. In this study, the importance, definition, variability and estimation methods of HI in crop models were discussed. HI estimation methods are categorized into two groups including: (i) complex methods that estimate HI from the beginning of seed gro...

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