Using compost and soil amendments is beneficial to Florida citrus groves. Given the sandy nature of Florida soils and their low organic matter and cation exchange capacity (CEC), adding compost and ...organic amendments (e.g., humic acid) can enhance the ability of soil to retain water and nutrients. These practices can also boost soil microbial activity and improve soil health. Previous research has shown that yield losses from huanglongbing (HLB) affected trees correlate with low fibrous root densities and reduced root system capacity for water and nutrient uptake. Compost and organic amendments can thus aid citrus growers by improving overall soil physical, chemical, and biological properties. However, any strategies to boost tree growth can also potentially boost weed growth. So it is essential to understand the impacts of these soil management practices on weed emergence and infestation in citrus groves.
Chemical weed control is an essential component of the ‘weed control toolbox’ for keeping the weeds checked in citrus groves. Citrus growers primarily rely on herbicides to manage weeds due to their ...efficacy and cost-effectiveness. However, despite their benefits, herbicides may produce a wide range of unintended effects in citrus. For instance, an herbicide-related injury may occur due to improper spay practices, unfavorable weather conditions, product misapplication, tank contamination, or herbicide carryover from the past application. Moreover, the movement of herbicides as a result of drift, volatilization or runoff, either on-site or from applications on adjoining areas, can also result in tree injury. This article discusses the diagnosis of such injuries from commonly used herbicides in citrus production.
Adjuvants are materials added into a herbicide spray mix that improves the herbicide’s performance, especially its handling, application efficacy, and crop-safety. Examples of adjuvants include ...surfactants, drift control agents, buffering agents, etc. For instance, surfactants (surface active agents) are an adjuvant designed for improving the coverage, foliar retention, and penetration of a herbicide spray mixture. This article will discuss various types of adjuvants and their utility in enhancing weed control efficacy and tree-safety in citrus weed management.
Laser weeding may contribute to less dependency on herbicides and soil tillage. Several research and commercial projects are underway to develop robots equipped with lasers to control weeds. ...Artificial intelligence can be used to locate and identify weed plants, and mirrors can be used to direct a laser beam towards the target to kill it with heat. Unlike chemical and mechanical weed control, laser weeding only exposes a tiny part of the field for treatment. Laser weeding leaves behind only ashes from the burned plants and does not disturb the soil. Therefore, it is an eco-friendly method to control weed seedlings. However, perennial weeds regrow from the belowground parts after the laser destroys the aerial shoots. Depletion of the belowground parts for resources might be possible if the laser continuously kills new shoots, but it may require many laser treatments. We studied how laser could be used to destroy the widespread and aggressive perennial weed Elymus repens after the rhizomes were cut into fragments. Plants were killed with even small dosages of laser energy and stopped regrowing. Generally, the highest efficacy was achieved when the plants from small rhizomes were treated at the 3-leaf stage.
Weed management is a critically important activity on both agricultural and non-agricultural lands, but it is faced with a daunting set of challenges: environmental damage caused by control ...practices, weed resistance to herbicides, accelerated rates of weed dispersal through global trade, and greater weed impacts due to changes in climate and land use. Broad-scale use of new approaches is needed if weed management is to be successful in the coming era. We examine three approaches likely to prove useful for addressing current and future challenges from weeds: diversifying weed management strategies with multiple complementary tactics, developing crop genotypes for enhanced weed suppression, and tailoring management strategies to better accommodate variability in weed spatial distributions. In all three cases, proof-of-concept has long been demonstrated and considerable scientific innovations have been made, but uptake by farmers and land managers has been extremely limited. Impediments to employing these and other ecologically based approaches include inadequate or inappropriate government policy instruments, a lack of market mechanisms, and a paucity of social infrastructure with which to influence learning, decision-making, and actions by farmers and land managers. We offer examples of how these impediments are being addressed in different parts of the world, but note that there is no clear formula for determining which sets of policies, market mechanisms, and educational activities will be effective in various locations. Implementing new approaches for weed management will require multidisciplinary teams comprised of scientists, engineers, economists, sociologists, educators, farmers, land managers, industry personnel, policy makers, and others willing to focus on weeds within whole farming systems and land management units.
Maintaining vegetation between the tree rows is essential in citrus groves to reduce soil erosion from rain and wind. However, the growth of this vegetation needs to be suppressed effectively to ...prevent their invasion into herbicide treated tree rows or under-tree areas. The row-middle weed management in citrus can be accomplished by several strategies including mechanical (e.g., mowing), chemical (e.g., herbicide wiping), cultural (e.g., cover crops), or by utilizing a combination of these strategies (e.g., chemical mowing). Peer reviewed through UF/IFAS Citrus Research and Education Center; published in Citrus Industry Magazine
Weeds compete with young citrus trees for nutrients, moisture, etc. and may hinder their successful establishment. Moreover, young trees are more susceptible to damage from herbicide applications ...compared with mature and established trees. Hence careful and crop safe weed control is a crucial component for newly planted citrus trees. This trade journal article will cover the different aspects of weed management strategies in a new grove planting or a resetting program.
Changes in the weed flora of cropping systems reflect the impacts of factors that create safe sites for weed establishment and facilitate the influx and losses to and from the soil seedbank. This ...analysis of the annual surveys of the Southern Weed Science Society documents changes in the weed flora of the 14 contiguous southern states since the advent of transgenic, herbicide-resistant crops. In 1994 and 2009, the top five weeds in corn were morningglories, Texas millet, broadleaf signalgrass, johnsongrass, and sicklepod; in this same period Palmer amaranth, smartweeds, and goosegrass had the greatest increases in importance in corn. In cotton, morningglories and nutsedges were among the top five most troublesome weeds in 1995 and 2009. Palmer amaranth, pigweeds, and Florida pusley were also among the five most troublesome species in 2009; the weeds with the largest increases in importance in cotton were common ragweed and two species with tolerance to glyphosate, Benghal dayflower and Florida pusley. In soybean, morningglories, nutsedges, and sicklepod were among the top five weed species in 1995 and 2009. Two species with glyphosate resistance, Palmer amaranth and horseweed, were the second and fourth most troublesome weeds of soybean in 2009. In wheat, the top four weeds in 2008 were the same as those in 1994 and included Italian ryegrass, wild garlic, wild radish, and henbit. Crop production in the southern region is a mosaic of various crop rotations, soil types, and types of tillage. During the interval between the surveys, the predominant change in weed management practices in the region and the nation was the onset and rapid dominance of the use of glyphosate in herbicide-resistant cultivars of corn, cotton, and soybean. Because of the correspondence between the effects of glyphosate on the respective weed species and the observed changes in the weed flora of the crops, it is likely the very broad use of glyphosate was a key component shaping the changes in weed flora. Only eight of the top 15 most troublesome weeds of cotton and soybean, the crops with the greatest use of glyphosate, were the same in 1995 and 2009. In contrast, in corn and wheat where adoption of glyphosate-resistant cultivars lags or is absent, 12 of the 15 most troublesome weeds were the same in 1994 and 2008. These findings show on a regional scale that weeds adapt to recurrent selection from herbicides, currently the predominant weed management tool. Future research should seek methods to hinder the rapid spread of herbicide-tolerant and evolution of herbicide-resistant weed species. As new tools are developed, research should focus on ways to preserve the efficacy of those tools through improved stewardship. Nomenclature: annual bluegrass, Poa annua L. POAAN; Benghal dayflower, Commelina benghalensis L. COMBE; broadleaf signalgrass, Urochloa platyphylla (Nash) R.D. Webster BRAPP; common ragweed, Ambrosia artemisiifolia L. AMBEL; Florida pusley Richardia scabra L. RCHSC; goosegrass Eleusine indica (L.) Gaertn. ELEIN; groundcherries, Physalis spp.; henbit, Lamium amplexicaule L. LAMAM; horseweed, Conyza canadensis (L.) Cronq. ERICA; Italian ryegrass, Lolium perenne L. ssp. multiflorum (Lam.) Husnot LOLMU; johnsongrass, Sorghum halepense (L.) Pers. SORHA; morningglories, Ipomoea spp.; nutsedges, Cyperus spp.; Palmer amaranth, Amaranthus palmeri S. Wats. AMAPA; pigweed, Amaranthus spp.; sicklepod, Senna obtusifolia (L.) H.S. Irwin & Barneby CASOB; smartweeds, Polygonum spp.; Texas millet, Urochloa texana (Buckl.) R. Webster PANTE; wild garlic, Allium vineale L. ALLVI; wild radish, Raphanus raphanistrum L. RAPRA; corn, Zea mays L.; cotton, Gossypium hirsutum L.; soybean Glycine max. (L.) Merr.; wheat, Triticum aestivum L.
Citrus requires ‘weed-free’ tree rows for healthy growth and fruit production by reducing competition from the weeds. Many weed species can be managed by developing an herbicide program, depending on ...factors like the type of weeds, stage of weed growth, grove location, etc. However, certain weeds are tough to control and may require selective and timely herbicide applications, for instance, goatweed. When compared to other weed species, goatweed is relatively tolerant to many of the herbicides used in citrus. If not appropriately managed in its early growth stage, goatweed will spread quickly in the grove and will become a problematic weed in no time. This article is aimed to provide citrus growers some strategies to manage such problem weeds in their groves.
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