- Author: Elizabeth J Fichtner
- Author: Katherine Mae Culumber
- Translator: Charlotte Burks
Usted ha notado que enteros cultivos maduros se han reducido a montones de astillas en solo días? Lo que estás viendo se llama “reciclo de cultivos enteros”, y es un método de facilitar la descomposicion de la tierra y preservar la calidad del aire en el valle central de California.
El paisaje del condado de Tulare ha cambiado dramáticamente por la eliminación de los cultivos. Las nueces que están desapareciendo son especialmente importantes en esta área porque las nueces son los originales cultivos de nueces de Tulare County,con plantaciones o apareciendo en la década del 1930. Varios factores han contribuido a la eliminación de cultivo de nueces en la región, incluyendo un cambio drastico en precios de frutos secos , ()especialmente nueces , y la imposición de regulaciones del uso de agua subterránea. Las economías de producción de nueces han sido impactadas en una manera negativa por disputas de comercio, nuevos competidores internacionales en producción de nueces , huelgas en los puertos, y más recientemente, la calidad pobre de la cosecha de 2022, una consecuencia probablemente de la ola de calor tarde en el verano antes de cosechar. Finalmente, muchas áreas históricas de crecimiento de nueces, referidas como “tierras blancas”, son parte de áreas no cubiertas por distritos de irrigación agricultural, donde la irrigación es creada solo desde sacar agua de la tierra. Regulaciones recientes impuestas en sacar agua subterránea han necesitado la eliminación de cultivos permanentes en parte de estos acres.
Cuando un cultivo ha llegado al fin de la parte de su vida en que es económicamente productiva, productores se encuentran con el trabajo de disponer del biomass de astillas. Históricamente, los árboles se empujaban y quemaban; pero quemar varios árboles daña la calidad del aire en la región. Adicionalmente, quemando inmediatamente suelta cenizas a la tierra llenas de nutrientes y guardaban carbono en el aire como dióxido de carbono, un gas de invernadero. Reciclar enteros cultivos deja que una porción significante del carbono producido en fotosíntesis durante la vida del cultivo sea devuelto a la tierra en lugar de perderlo en el ambiente. Además, los nutrientes guardados dentro de los biomas son gradualmente soltados a la tierra mientras las astillas se descomponen, contribuyendo a las necesidades de los próximos cultivos.
Reciclar enteros cultivos se cumple por cortar los biomas de astillas y extender lo que queda por todo el área del cultivo. Las astillas, aún más pequeñas, se incorporan a la primera capa de tierra, donde la tierra microbial procesa las astillas. Mientras mueren las microbacterias, los nutrientes quedan guardados dentro de los biomas (los cuerpos de millones de bacterias y fungos) y son retornadas a la tierra. Después del reciclaje de cultivos enteros, la tierra se puede dejar en un periodo no reproductivo , o puede ser replantado con cultivos continuos o anuales, dependiendo en el mercado y en cuánta agua hay disponible. Aunque el paisaje local está cambiando dramáticamente, nosotros podemos apreciar que los productores están asegurando que los beneficios de subproductos agrícolas no son perdidos desde el sistema local agronomo, y que podemos esperar observar las futuras fases del uso de la tierra en nuestra región.
foto: Enteros cultivos son reciclados por cortar las astillas biomas e incorporar el prod
ucto de esto a la primera capa de la tierra, un proceso llamado reciclo de cultivo entero.
- Author: Elizabeth J Fichtner
Visalia students at Linwood Elementary were introduced to prunes as a local crop and a nutritious snack during today's “Try it Tuesday” event hosted by teachers, Julie Cates and Bethany Gonzales. Elizabeth Fichtner, UCCE Tulare County Farm Advisor, visited 1st and 6th grade classes with a prepared talk on the culture of prunes followed by a tasting. Students were taught about prune cultivation, harvest technology, and post-harvest processes from transportation to dehydration.
Sixth grade students were paired with their first-grade buddies for a tasting in concert with learning fun facts about the factors contributing to the sweetness of prunes as well as secondary uses of the fruit in the commercial food industry.
Prunes are an important specialty crop in Tulare County valued at over $15.3 million (Tulare County Ag Commissioner Crop Reports, 2021). Currently, Tulare County has just over 2,500 acres of prunes in the ground.
- Author: Elizabeth J Fichtner
- Author: Charlotte Burks
- Author: Mel Thayer
- Author: Robert Van Steenwyk
Walnut scale (Figure 1A) is an important economic pest of walnuts in California. High populations of walnut scale may affect tree vigor as well as predispose trees to diseases caused by several plant pathogenic fungi. Historic UC Pest Management Guidelines emphasize the efficacy of insecticide applications at the delayed dormant (March) stage of plant development or at the early crawler stage (late April-early May) (Figure 1B) of insect development. Both walnut scale and frosted scale overwinter as immature nymphs; therefore dormant application of insect growth regulators (IGRs) has the potential to inhibit maturation and subsequent reproduction of these pests. New research is needed to evaluate the efficacy of dormant IGR treatments for management of walnut and frosted scale.
In 2023, UC ANR and UC Berkeley researchers initiated a new collaborative study investigating the efficacy of four products applied at various rates and times (Table 1). Two insect growth regulator products, Esteem® (IRAC Group 7C) and Centaur® (IRAC Group 16), were included in the study, with both dormant (February 8, 2023) and early crawler-stage (April 26, 2023) application timings. Centaur® was also investigated at two rates. Early crawler-stage applications of Senstar (a combination of spirotetramat and pyroxifin) and Assail 20SG (a neonicitinoid) were also included in the study.
The study will address the impact of dormant IGR applications on populations of viable adult frosted scale and walnut scale in late April, just prior to anticipated walnut scale crawler emergence. Additionally, the influence of all treatments on walnut scale crawler populations will be evaluated. The results from the study will be shared on the UCCE San Joaquin Valley Trees and Vines website (https://www.sjvtandv.com/) and in the UCCE Tulare County's “In a Nutshell newsletter”.
- Author: Elizabeth J Fichtner
- Author: Mae Culumber
The unusually wet winter and spring of 2023 has had unprecedented impacts on our local orchard systems. However, the cumulative impacts of a barrage of atmospheric rivers and persistent standing water in some flooded areas may not be realized for another year. Cold and rainy conditions during bloom limited pollinator activity and impeded orchard access for spray operations, creating the ideal conditions for the onset of plant pests and disease issues. The timing of bud and shoot development has likely also been impacted, as the buds for next year's crop are formed during the current year; therefore, the unusually wet and cold spring of 2023 may also influence the development of the 2024 crop.
The bloom period for many Prunus species (almond, peach, cherry, plum, prune, etc.) was unusually protracted due to the high frequency of rain and cool temperatures. Saturated soil conditions limited orchard access, resulting in delayed shaking of mummy nuts in almond, an essential sanitation practice for management of navel orangeworm, a key insect pest (Figure 1A). With few bee flying hours available for pollination, and wet, cold conditions conducive to disease development (Figure 1 B,C and D), the crop outlook for 2023 remains uncertain.
Pistachio, walnut, and pecan, all wind-pollinated crops, are experiencing delayed bud break and shoot development. The progression of bud break appears to be at least 10 days behind the norm and the timing and synchrony of male and female flower maturity is yet unknown.
Orchards that have sustained flooding may be physiologically impacted by roots persistence in anoxic conditions and may also be exposed to waterborne plant pathogens. Over time saturated soil will become depleted of oxygen by the roots and microbial communities resulting in anoxic conditions that can lead to root mortality. The extent of damage to the roots may not be realized until the season progresses, and root damage may manifest with general canopy decline and anchorage issues. Many of the tree crops grown in California are grafted onto disease resistant rootstocks. If flood water rises above the graft union, the benefit of these rootstocks is largely negated. Many rootstocks have been selected over time for resistance to Phytophthora spp., a group of soilborne pathogens that create motile spores that swim at the water surface. These pathogens are common in surface water, and incite canker diseases, particularly when the water level persists above the graft union. Symptoms of infection include general canopy decline and cankers, many of which ooze or ‘bleed' (Figure 1C). The full suite of symptoms may not manifest until further into the growing season when the heat imposes stress on the trees.
The rainfall and flooding have additionally influenced the nutritional status of orchard soils. Cool, wet soil conditions slow the chemical and biological reactions that control the availability of nutrients for tree uptake. Micronutrients, present in only trace concentrations in soil, become particularly limited as the wet and cold create reductive conditions that promote lime-induced iron chlorosis, a common nutritional deficiency in prunes, almonds, and citrus (Figure 1 E). In sites that have undergone whole orchard recycling with incorporation of woody biomass into the soil, saturated, anaerobic conditions may moderate the microbial activity needed to stimulate wood chip decomposition and further restrict nutrient availability until the soil warms.
As rivers breach their banks, rushing floodwater may transport the less-soluble nutrients, such as sulphate of potash (SOP) that is often applied in the autumn, away from the tree rootzone. As water moves through the soil profile, other nutrients, such as nitrogen, may be lost from the rootzone by leaching. The leaching will, however, ameliorate salt accumulation after years of drought, particularly in sites that have relied on saline groundwater for irrigation.
As the season progresses, growers should work closely with their PCAs, crop consultants, and UCCE farm advisors to observe and document orchard changes in the 2023 season. Photographs should be taken of anomalies, such as delayed bud break, so comparisons may be made to past and future years. Additionally, photos of putative disease and insect issues may easily be shared with representatives from private industry as well as researchers in the UC system for both diagnosis and discussion of best management strategies. A suite of photos and management options for the most common pest and diseases of agricultural crops can be found at the UC IPM website (www.ipm.ucdavis.edu).
- Author: Cameron Zuber
- Author: Elizabeth J Fichtner
The removal of nuts remaining on almond trees from the prior year's crop is an important winter sanitation practice for the management of navel orangeworm (NOW), Amyelois transitella. Residual nuts are called ‘mummies' and the process of removing the mummies is referred to as a ‘mummy shake' because they are mechanically shaken from trees. This practice is conducted during the dormant and delayed dormant season, a time when orchard access may be thwarted by the winter rains.
Most growers strive to have the mummy shake complete by mid-January when buds are dormant and less likely to abscise from the vibration caused by a mechanical shaker. As the flower buds progress toward bloom, they become more sensitive to the shaker vibration and more likely to abscise. Studies conducted in the 1980s (Sibbett et al.) established that the shaking of mummies by January 31 (approximately 8 days prior to bloom) at a Kern County site did not adversely affect yield; however, the authors cautioned growers of the risk of delaying mummy shakes further, particularly on early blooming varieties and in locations in the southern San Joaquin Valley1. Because bud development and bloom date advance with increasing latitude, the potential risk of early and mid-February mummy shakes was investigated by W. Asai (Pomology Consulting, Turlock, CA) in the northern San Joaquin Valley. This work, conducted at a more northern latitude, suggested shakes conducted in early February may not compromise yield2.
The lack of yield detriment attributed to a mummy shake-mediated bud loss may seem counterintuitive; however, simple concepts of tree physiology may help explain this phenomenon. Consider that only approximately 30% of the flowers on a tree set a crop. A given tree does not have the carbohydrate stores needed to set every flower. As a result, the loss of a subset of flower buds may have little effect on overall yield. Naturally, the risk of crop loss increases the closer the shake approaches bloom, and both research groups suggested that mummy shakes be complete prior to the pink bud stage of development.
Although rainy years make it difficult for growers to access orchards and complete orchard sanitation tasks, the heightened soil moisture adversely affects NOW survival in comparison to dry winters. Mummy nuts on the ground support enhanced NOW survival on a dry orchard floor than on moist soil with winter vegetation in the row middles. The next step in managing overwintering populations of NOW is destruction of mummies by flailing or mowing. Flailing and mowing should be completed by March 1, prior to the emergence of NOW. The emergence profile of NOW varies by location, but the first flight generally starts in late March.
Growers who have not completed their winter sanitation practices by the end of January should walk their orchards to assess bud development in consideration of a delayed mummy shake. Winter sanitation can reduce now damage by up to 80%, so an early February shake may be worth the effort if orchard access is possible and bud development has not advanced into pink tip. For more information on NOW management, visit www.ipm.ucdavis.edu.