Germán V. Sandoya

University of Florida | UF · Department of Horticultural Sciences

The use of high tunnels, which allows growers to extend their season and improve yields, is increasing in the Southeastern U.S., yet growers face challenges related to weed and disease management, particularly in organic systems. On-station experiments were conducted during fall 2021 and spring 2022 in a split-plot design to assess the efficacy of...

Verticillium wilt, caused by Verticillium dahliae, is one of the most devastating soilborne diseases of lettuce (Lactuca sativa L.). There are three races of V. dahliae and each race has been characterized by markers representing race-specific effectors. Race 1 is differentiated by the presence of the functional secretory Ave1 effector. Similarly,...

Lettuce is a highly perishable horticultural crop with a relatively short shelf-life that limits its commercial value and contributes to food waste. Postharvest senescence varies with influences of both environmental and genetic factors. From a larger pool of romaine lettuce genotypes, we identified three genotypes with variable shelf lives and eva...

Warmer temperatures during crop production are not desirable for a cool-season crop such as lettuce ( Lactuca sativa L.). Lettuce is among the top 10 most consumed vegetables in the United States. Production of this vegetable is concentrated mostly in temperate areas of California, and during the wintertime in Arizona and Florida as a result of the...

Corynespora cassiicola ( Cc ) is a genetically diverse ascomycete found worldwide in tropical and subtropical regions. Cc causes necrotrophic diseases in several plant species, including important crops such as rubber tree, tomato, cotton, and cucumber. Evidence suggests the involvement of one or more Cc host-specific toxins in disease progression....

Chapter 9 of the Vegetable Production Handbook of Florida

Pink rib discoloration or pinking in the midribs of lettuce ( Lactuca sativa ) leaves is a stress-induced disorder that leads to crop loss worldwide. Maintaining recommended field and postharvest conditions reduces its incidence but does not eliminate the issue. During the past decade, research has identified the tolerance of this disorder among le...

Growing vegetables in controlled environments (CEs), such as hydroponics, aquaponics, and vertical structures, is a rapidly expanding industry in Florida and the United States, especially in nearby urban areas. Although lettuce ( Lactuca sativa ) is still mostly produced in fields, growing in CEs proximal to urban areas has become increasingly popu...

Lettuce (Lactuca sativa L.) is the most common leafy vegetable produced hydroponically in the United States. Although hydroponic systems are advantageous due to lower pest and disease pressure, and reduced water and nutrient requirements, the increasing prices of fertilizers, including phosphorus (P), still influences the profitability of hydroponi...

Lettuce ( Lactuca sativa L.) is one of the most consumed fresh vegetables in the United States. However, lettuce production is heavily limited to California and Arizona, posing a high risk to the supply chain. Hydroponic production is a soilless cultivation method and provides a sustainable alternative to growing lettuce in the field. Light is a cr...

Este artículo describe las prácticas de manejo de cultivo requeridas para la producción de lechuga de campo en Florida y para ayudar a los productores a tomar decisiones de manejo que ayudarán a controlar la mancha bacteriana de la lechuga. A translation of HS1412, by Byron Manzanero, Germán Sandoya, and D. C. Odero; published by the UF/IFAS Hortic...

Chapter 9 of the Vegetable Production Handbook.

Bacterial Leaf Spot (BLS) is a disease that threatens lettuce (Lactuca sativa L.) production in warmer temperatures and high relative humidity, conditions that are conducive to unpredictable disease outbreaks and thus potentially resulting in total crop loss. BLS also causes problems in other major lettuce producing areas in the US and worldwide. T...

Spring mix is a popular packaged salad that contains lettuce (Lactuca sativa L.) as one of its main ingredients. Plants for baby leaf lettuce (BLL) production are grown at very high densities, which enhances the occurrence of bacterial leaf spot (BLS) caused by Xanthomonas hortorum pv. vitians (Xhv), a disease that can make the crop unmarketable. T...

Most agricultural soils worldwide have limited availability of phosphorus (P); thus, crops require supplemental application of P fertilizers. Due to the economic and environmental concerns derived from the use of P fertilizers, identifying and breeding P-efficient lettuce (Lactuca sativa L.) cultivars is imperative for the reduction of production c...

This publication presents an overview on the use of different small hydroponic systems that could be implemented by home gardeners. Recommendations on lighting, media, and other key aspects are presented in this publication as well. Spanish translation of HS1422, Growing Lettuce in Small Hydroponic Systems, by Germán V. Sandoya, Jonael Bosques, and...

Fusarium wilt of lettuce is caused by the pathogen Fusarium oxysporum f. sp. lactucae ( Fol ) and is a growing threat to global lettuce production. Fol was first detected in Florida in 2017 and was subsequently confirmed as race 1. Management strategies for this long-persisting soil pathogen are limited, time-consuming and expensive, and they may l...

The global demand for P fertilizers has been significantly increasing, resulting in higher costs and environmental concerns associated with eutrophication. Fertilizer expenses and environmental risks can be reduced through the implementation of sustainable strategies. This new 6-page publication of the UF/IFAS Horticultural Sciences Department comp...

This new 6-page publication of the UF/IFAS Horticultural Sciences Department presents an overview on the use of different small hydroponic systems that could be implemented by home gardeners for lettuce. Recommendations on lighting, media, and other key aspects are presented in this publication as well. Written by Germán V. Sandoya, Jonael Bosques,...

Field and vegetable crops are primary source of food. Field crops are also a rich source of cellulosic biomass and carbohydrates for biofuels. One of the major challenges facing agriculture today is improving the productivity of crops in an environmentally sustainable manner. Annual climate variation causes temperature extremes, floods, and drought...

Chapter 9 of the Vegetable Production Handbook.

The postharvest life of lettuce ( Lactuca sativa ) is variable and negatively affected by mechanical injury, incomplete cooling, and poor genetic quality. Lettuce breeders are developing cultivars with a longer shelf life and rely on subjective, destructive, and time-consuming methods for quality analysis. One method of accelerating quality evaluat...

Lettuce is the most popular ingredient in salads and salad mixes consumed in the United States. Florida's subtropical climate facilitates lettuce production from fall through spring, but the warm and moist conditions are also favorable for insect proliferation and damage. Insect pests cause direct (feeding) and indirect (contamination) damages to t...

This new 8-page publication of the UF/IFAS Horticultural Sciences Department explains which nutrients are abundant among the major lettuce types compared to other leafy vegetables, encourages consumers to help satisfy dietary recommendations by eating lettuce at appropriate serving sizes, and outlines the basic growing conditions that help maximize...

Most agricultural soils worldwide present limited availability of phosphorus (P) and crops require supplemental application of P fertilizers. Due to the economic and environmental concerns derived from the use of P fertilizers, identifying and breeding P-efficient lettuce ( Lactuca sativa L.) cultivars is imperative for the reduction of production...

Bacterial leaf spot (BLS) of lettuce is caused by the bacterium Xanthomonas hortorum. BLS is more damaging in Florida, where the climate is conducive for disease development. The most effective control method is host resistance currently being developed by the UF/IFAS lettuce breeding program in all lettuce types. This new 4-page publication of the...

Verticillium dahliae, the soilborne fungal pathogen, causes vascular wilt on many economically important crops, resulting in significant yield losses. V. klebahnii (isolate PD659) and V. isaacii (isolate PD660), two related species that cause few or no symptoms in some hosts, were evaluated as potential biocontrol agents (BCAs) in eggplant, lettuce...

In south Florida sugarcane is cultivated on muck and sandy soils. The cane yield (CY) of varieties grown on sandy soils is substantially lower than on muck soils due to water and nutrients stress. High CY combined with good ratooning ability (RA) is important for profitable sugarcane cultivation. In this study three series of CP trials (CP 2009, CP...

Sorghum (Sorghum bicolor L.) has the potential to become a widespread commercial feedstock crop in Pennsylvania, either in rotation with maize (Zea mays L.) or grown alongside it. In other locations where sorghum has been grown for a long time, it is attacked by Colletotrichum sublineola Henn. ex Sacc. & Trotter, a fungal pathogen that causes anthr...

Lettuce Downy Mildew (LDM), caused by the oomycete Bremia lactucae , is the most important disease of lettuce worldwide. LDM has a direct effect on both yield quantity and quality because it may infect lettuce at any growth stage, affecting the marketable portion of the crop. This new 6-page publication of the UF/IFAS Horticultural Sciences Departm...

Liriomyza trifolii (Diptera: Agromyzidae) is a leafminer that causes ruinous damage to many leafy vegetables including lettuce ( Lactuca sativa L.) by stippling and tunneling the leaves. In this study, a population of 125 F 3 families was developed from the intraspecific cross of ‘Valmaine’ (resistant) and ‘Okeechobee’ (susceptible) romaine cultiva...

Lettuce ( Lactuca sativa L.) is a cool season crop that is vulnerable to high temperature stress, which promotes bolting and decreases yield and quality. It is anticipated that climate change may lead to higher temperatures in current lettuce growing areas in the United States, thereby negatively affecting lettuce production and possibly resulting...

Este artículo tiene como objetivo informar al público en general, administradores de tierras, investigadores, autoridades locales y estatales, y a todo aquel que busque orientación para acceder a listados de plantas no autóctonas en el estado de Florida, tanto normativos como no normativos. En este documento se explica el origen de las listas, el s...

Lettuce ( Lactuca sativa L.) is planted in Florida starting late fall at the end of September and continuing through the last harvest in May. In recent years, the season has shortened because of warm temperatures and weather-related events, such as rainfall at the beginning and the end of the season. During the transition between summer production...

Lettuce (Lactuca sativa L.) is one of the most economically important vegetables in the USA with approximately 50% of the domestic production concentrated in the Salinas Valley of California. Verticillium wilt, caused by races 1 and 2 of the fungal pathogen Verticillium dahliae Kleb., poses a major threat to lettuce production in this area. While r...

Fusarium wilt of lettuce is a disease caused by the fungus Fusarium oxysporum f.sp. lactucae. The disease is present in all lettuce production areas worldwide. Recently this disease has been identified in Florida in localized fields. This new 4-page publication of the UF/IFAS Horticultural Sciences Department presents information about the disease,...

Bacterial leaf spot (BLS) is a disease that affects lettuce (Lactuca sativa L.) worldwide. The disease is caused by the bacterium Xanthomonas campestris pathovar vitians (Xcv), which exclusively infects lettuce and is particularly devastating in warm humid climates. Reine des Glaces (RG), an old Batavia-type cultivar, exhibited an uninvestigated pa...

Understanding pathogen evolution over time is vital for plant breeding and deployment of host resistance. In the context of a soilborne pathogen, the potential of host-directed evolution of a Verticillium dahliae race 1 isolate and genotypic variation of V. dahliae associated with two major hosts (lettuce and tomato) were determined. A total of 427...

Verticillium wilt caused by Verticillium dahliae Kleb. is an economically damaging disease of iceberg lettuce on the Central Coast of California. Foliar wilting symptoms that manifest near or at peak market maturity (MM) lead to collapse of the head, making it unmarketable. Complete resistance to race 1 of the pathogen is known, but adequate levels...

Background Plants can respond to insect attack via defense mechanisms that reduce insect performance. In this study, we examined the effects of several treatments applied to two maize genotypes (one resistant, one susceptible) on the subsequent growth and survival of Sesamia nonagrioides Lef. (Mediterranean corn borer, MCB) larvae. The treatments w...

Global warming poses serious threats and challenges to the production of leafy vegetables. Being a cool-season crop, lettuce is particularly vulnerable to heat stress. To adapt to climate change, this study was conducted to evaluate the performance of leaf lettuce genotypes for heat tolerance by growing them in different locations within California...

Race 1 resistance against Verticillium dahliae in lettuce was originally shown in the cultivar La Brillante to be conditioned by a single dominant gene (Verticillium resistance 1, Vr1). Multiple, morphologically diverse sources of germplasm have been identified as resistant to race 1. In this study, allelism tests indicated that resistance in these...

Verticillium wilt, caused by Verticillium dahliae, is an important disease of cotton worldwide. Isolates of V. dahliae can be characterized as race 1 or race 2 based on the responses of differential cultivars of tomato and lettuce, or as defoliating or nondefoliating based on symptom expression in cotton. To investigate the frequency and distributi...

Verticillium wilt caused by Verticillium dahliae is an important soilborne disease of pepper (Capsicum species) worldwide. Most commercial pepper cultivars lack resistance to this pathogen. Our objective was to identify resistance to two V. dahliae isolates in wild and cultivated Capsicum accessions from the core collection of the National Plant Ge...

Verticillium is a genus that includes major vascular wilt pathogens. Recently, multilocus phylogenetic analyses of the genus identified five new species, including Verticillium isaacii and V. klebahnii, both of which occur in agricultural soils in coastal California and have been isolated from asymptomatic and diseased spinach and lettuce plants. L...

Verticillium dahliae is a soilborne, economically significant fungal plant pathogen that persists in the soil for up to 14 years as melanized microsclerotia (ms). Similarly, V. longisporum is a very significant production constraint on members of Brassicaceae. Management of Verticillium wilt has relied on methods that reduce ms below crop-specific...

Verticillium longisporum is an economically important vascular pathogen of Brassicaceae crops in different parts of the world. Verticillium longisporum is a diploid hybrid that consists of three different lineages, each of which originated from a separate hybridization event between two different sets of parental species. We used 20 isolates repres...

Verticillium wilt of lettuce is caused by two races of the fungus Verticillium dahliae. Complete resistance to race 1 is conferred by the Vr1 gene, while only partial resistance to race 2 is known. Additional sources of race 2 or race non-specific resistance are needed. The disease causes discoloration of root vascular tissues followed by wilting o...

Verticillium wilt in lettuce (Lactuca spp.) is a threatening disease caused by the soil borne fungus Verticillium dahliae. In lettuce, two races of the pathogen are known (race 1 and 2). Resistance to race 1 is controlled by a single dominant gene named Verticillium resistance 1 (Vr1) located on linkage group 9 in 'La Brillante'. Several other lett...

Various pests, such as those in the order Lepidoptera, frequently feed on young maize (Zea mays) plants and pose a significant threat to plant development and survival. To manage this problem, maize generates a wide variety of responses to attack by pests, from activation of wound-response pathways to the release of volatile compounds. Mp708, an in...

Fall armyworm is comprised of two sympatric and morphologically identical strains that are genetically distinct and defined by their nutritional ecology. Populations of the corn strain are almost exclusively found feeding on large grasses (e.g., corn), while populations of the rice strain are primarily found feeding on small grasses (e.g., rice, be...

Several maize, Zea mays L., inbred lines developed from an Antiguan maize population have been shown to exhibit resistance to numerous aboveground lepidopteran pests. This study shows that these genotypes are able to significantly reduce the survival of two root feeding pests, western corn rootworm, Diabrotica virgifera virgifera LeConte, and south...

Mediterranean corn borer (MCB) (Sesamia nonagrioides Lef) and European corn borer (ECB) (Ostrinia nubilalis Hbn) are the most important biotic stresses of maize in Europe. The first selection program to improve stalk resistance to MCB was carried out in the maize population EPS12. It has shown that selection was effective to improve stalk resistanc...

A maize synthetic population was improved for resistance to the Mediterranean corn borer (MCB, Sesamia nonagrioides) while maintaining yield. The objectives of this research were to investigate whether yield and yield stability of the maize synthetic population named EPS12 were affected by selection for MCB resistance; also to determine which genot...

In maize, the Mediterranean corn borer (MCB), Sesamia nonagrioides Lef, is the insect pest that causes the most significant yield losses in north-western Spain. A S1 recurrent selection program to improve resistance of EPS12 against MCB was evaluated previously. In the current study two experiments were conducted to determine if antibiosis and/or s...

The Mediterranean corn borer or pink stem borer (MCB, Sesamia nonagrioides Lefebvre) causes important yield losses as a consequence of stalk tunneling and direct kernel damage. B73 and Mo17 are the source of the most commercial valuable maize inbred lines in temperate zones, while the intermated B73 x Mo17 (IBM) population is an invaluable source f...

Sesamia nonagrioides causes high yield losses in maize in northwestern Spain. Therefore, a recurrent selection programme to improve resistance against this pest has been carried out in a maize synthetic population. The main purposes of this investigation were to determine which are the main components of genetic variance for stem tunnelling and yie...

In northwestern Spain, the grounded whole kernel of flint maize (Zea mays L.) landraces is traditionally used for making bread and other bakery products. We have identified some local varieties appropriate for traditional bakery. Thus far, evaluations have been made under low corn borer pressure, but to know their ability to compete for yield and q...

Our knowledge of the genetics of resistance to the pink stem borer (Sesamia nonagrioides) in maize (Zea mays) is restricted to a few crosses among maize inbreds. The objectives of this study were to enlarge our understanding of the genetics of traits related to damage by pink stem borer and yield under infestation and to use generation means analys...

Recurrent selection has been reported as successful for improving maize resistance against corn borers. This study was conducted to determine if phenolics concentration in maize changes during recurrent selection to improve stalk resistance to the Mediterranean corn borer. Three cycles of selection [EPS12(S)C0, ESP12(S)C2, and EPS12(S)C3] from the...

Selection against pink stem borer (Sesamia non- agrioides Lef) (PSB) attack was performed in the maize (Zea mays L.) synthetic EPS12. The direct response of the EPS12 population to three cycles of selection to reduce tunnel length damage by PSB while maintaining yield was evaluated. S0 (cycles of selection) and S1 (selfed cycles of selec- tion) gen...

Early planting can contribute to increased grain yield of maize (Zea mays L.), but it requires cold tolerance. A limited number of cold-tolerant maize genotypes have been reported. The objectives of this study were to test a new strategy to improve cold tolerance in maize searching for broad x narrow genetic combinations that may be useful as base...

The leaf sheaths of selected inbred lines of maize (Zea mays L.) with variable levels of stem resistance to the Mediterranean corn borer Sesamia nonagrioides (Lefèvbre) were evaluated for antibiotic effect on insect development. Phytochemical analyses of leaf sheaths were conducted for cell wall phenylpropanoid content to gain a better understandin...

The pink stem borer (Sesamia nonagrioides Lef.) is the main corn (Zea mays L.) pest in the Mediterranean area. Although, screening for resistance to this pest has been successful, the level of resistance shown by the most resistant varieties is not high. The objectives of the present work were: (i) the evaluation for pink stem borer resistance of t...

Popcorn adapted to Spanish conditions could be an interesting and profitable alternative to field corn. However, little is known about breeding popcorn germplasm for adaptation to Spain. Sesamia nonagrioides Lefèvbre is the main insect pest affecting popcorn quality and yield under Spanish growing conditions. The objectives of the study were the se...

The pink stem borer (PSB) (Sesamia nonagrioides Lefèbvre, 1827; Lepidoptera: Noctuidae) is the main insect pest of maize (Zea mays L., Poaceae) in the Mediterranean area. Maize varieties partially resistant to PSB have been identified, but few studies have documented the mechanisms of resistance involved. The objectives of this research were to stu...

Comunicación presentada en el III Congreso de Mejora Genética de Plantas (Valencia, 13-15 de septiembre de 2006). El taladro del maíz (S. nonagrioides Lef) es la principal plaga que ataca a este cultivo en el área mediterránea. Con el objetivo de obtener variedades resistentes se inició en la Misión Biológica de Galicia un programa de selección rec...