Root rots

Beans are attacked by different pathogens. Rhizoctonia root rot results in seed rot, damping-off, stem canker, and root and pod rot. Fungicide applications are suggested as control measures. Fusarium root rot appears as reddish lesions or streaks on the hypocotyl and primary root. Fusarium yellows occurs on the roots and hypocotyls, usually at wound sites. Initial symptoms appear on lower leaves, which exhibit yellowing and wilting, becoming stronger and progressing upward to younger leaves. Control measures include crop rotation and chemical seed treatment. Pythium root rot is caused by various species of Pythium (P. ultimum, P. irregulare, P. aphanidermatum, and P. myriotylum). It can infect germinating seed, cotyledons, terminal buds, radicle, and hypocotyl tissue. Southern blight produces damping-off, stem blight, and root rot. Control can be achieved by selecting fields with low soil acidity and good drainage, wide plant spacing, lime, and crop rotation. Black root rot infects the hypocotyl. Numerous elongated lesions are produced on the stem and root tissues, resulting in plant stunting, premature defoliation, and eventual plant death. Texas root rot or Phymatotrichum root rot infects under-ground plant parts. Aboveground symptoms are stunting and sudden wilting at blossom initiation. Plants with Aphanomyces root-and-hypocotyl rot are stunted, clorotic, and suffer premature defoliation. Control measures for most of these diseases include proper cultural practices, use of chemicals, and resistant var. Color illustrations are given of the symptoms and damage caused by the diseases. (CIAT)El frijol es atacado por varios patogenos. La pudricion radical produce podredumbre del pie, chancro del tallo y pudricion radical y de la vaina. La pudricion seca de las raices aparece como lesiones rojizas en el hipocotilo y en la raiz primaria. El amarillamiento ocurre en las raices e hipocotilos, generalmente donde hay lesiones. Los sintomas iniciales aparecen en las hojas inferiores, las cuales muestran amarillamiento y marchitamiento, y se hacen mas pronunciados desplazandose hacia las hojas mas jovenes. Se controla con practicas culturales y tratamiento quimico de la semilla. La pudricion radical por varias especies de Pythium puede infectar la semilla en germinacion, los cotiledones, las yemas terminales, la radicula y el tejido del hipocotilo. El anublo sureno produce podredumbre del pie, anublo del tallo y pudricion radical. La pudricion negra de la raiz infecta el hipocotilo produciendo atrofiamiento, defoliacion prematura y muerte. La pudricion texana de la raiz o marchitamiento por Phymatotrichum omnivorum infecta las partes subterraneas de las plantas. Los sintomas en las partes aereas incluyen atrofiamiento y marchitamiento subito a la iniciacion de la florescencia. La pudricion por Aphanomyces y la pudricion del hipocotilo causan atrofia, clorosis y defoliacion prematura en las plantas severamente afectadas. Estas enfermedades se controlan con practicas culturales adecuadas, uso de quimicos y de var. resistentes. Se presentan ilustraciones a color de los sintomas y danos causados por las enfermedades. (CIAT

Nematodes

A fist of nematodes associated with the roots of beans and other plants is given in table form, the species of Meloidogyne and Pratylenchus being the most common in bean crops in the Americas. Meloidogyne species are prevalent in light sandy soils with good drainage. Length of survival in the soil depends on the nematode species, stage of development of the pathogen, soil type, moisture, and aeration. Color illustrations are given of the symptoms and damage caused by nematode feeding on root systems. They often appear on aerial plant parts which become chlorotic, stunted, burned at the leaf edges, and finally wilt. Crop rotation, deep plowing, the use of fallow, weed control, and flooding for 1-2 wk reduce nematode populations. Chemical control is effective but expensive and requires special equipment for soil applications. Control by plant resistance is the most efficient strategy. (CIAT)En forma de cuadro se presenta una lista de los nematodos que se asocian frecuentemente con las raices de frijol y otras plantas, siendo las especies de Meloidogyne y Pratylenchus las mas comunes en los cultivos de frijol en America. Las especies de Meloidogyne predominan en suelos arenosos livianos bien drenados. El periodo de supervivencia en el suelo depende de la especie de nematodo, el estado de desarrollo del patogeno, el tipo de suelo, la humedad y la temp. Se dan ilustraciones a color de los sintomas y danos ocasionados por los nematodos al alimentarse de los sistemas radicales. Estos se encuentran a menudo en las partes aereas de las plantas, las cuales se vuelven cloroticas, raquiticas, presentan quemazones en los bordes de las hojas y terminan marchitandose. La rotacion de cultivos, el arado profundo, el uso de barbecho, el control de malezas y las inundaciones durante 1-2 semanas disminuyen la poblacion de nematodos. El control quimico, aunque efectivo, es costoso y requiere equipo especial para hacer las aplicaciones al suelo. La estrategia mas efectiva es el control mediante el uso de var. resistentes. (CIAT

The Northern Root-Knot Nematode on Carrot, Lettuce, and Onion in New York

Root-knot nematodes (Meloidogyne spp.) are major pathogens of vegetables throughout the United States and world, impacting both the quantity and quality of marketable yields. In addition, root-knot nematodes interact with other plant pathogens, resulting in increased damage caused by other diseases. To date, only the northern root-knot nematode (NRKN; Meloidogyne hapla) has been found on vegetables grown on organic or mineral soil in New York, as it is able to survive the extreme low temperatures during winter. The NRKN has a wide host range consisting of more than 550 crop and weed species, including weeds common to muck soils such as dandelion (Taraxacum officinalis), purslane (Portulaca oleracea), mallow (Malva rotundifolia) and plantain (Plantago major). The increasing occurrence and damage of this nematode to onions, lettuce, and carrots grown on organic soils in New York was recently documented

A Soil Bioassay for the Visual Assessment of Soil Infestations of Lesion Nematode

NYS IPM Type: Vegetables IPM Fact SheetRoot-lesion nematodes (primarily, Pratylenchus penetrans) are major pathogens of vegetables in New York and the Northeast impacting both the quality and quantity of marketable yield. They are migratory endoparasites, indicating that they can be found in roots or in the soil surrounding the roots. Juvenile and adult stages can infect plant roots, causing considerable destruction of the cortical tissue

Use of an integrative soil health test for evaluation of soil management impacts

Understanding the response of soil quality indicators to changes in management practices is essential for sustainable land management. Soil quality indicators were measured for 2 years under established experiments with varying management histories and durations at four locations in New York State. The Willsboro (clay loam) and Aurora (silt loam) experiments were established in 1992, comparing no-till (NT) to plow-till (PT) management under corn (Zea mays L.)-soybean (Glycine max L.) rotation. The Chazy (silt loam) trial was established in 1973 as a factorial experiment comparing NT versus PT and the crop harvesting method (corn silage versus corn grain). The Geneva (silt loam) experiment was established in 2003 with vegetable rotations with and without intervening soil building crops, each under three tillage methods (NT, PT and zone-till (ZT)) and three cover cropping systems (none, rye and vetch). Physical indicators measured were wet aggregate stability (WAS), available water capacity (AWC) and surface hardness (SH) and subsurface hardness (SSH). Soil biological indicators included organic matter (OM), active carbon (AC), potentially mineralizable nitrogen (PMN) and root disease potential (RDP). Chemical indicators included pH, P, K, Mg, Fe, Mn and Zn. Results from the Willsboro and Aurora sites showed significant tillage effects for several indicators including WAS, AWC, OM, AC, pH, P, K, Mg, Fe and Mn. Generally, the NT treatment had better indicator values than the PT treatments. At the Chazy site, WAS, AWC, OM, AC, pH, K and Mg showed significant differences for tillage and/or harvest method, also with NT showing better indicator values compared to PT and corn grain better than corn silage. Aggregate stability was on average 2.5 times higher in NT compared to PT treatments at Willsboro, Aurora and Chazy sites. OM was also 1.2, 1.1 and 1.5 times higher in NT compared to PT treatments at Willsboro, Aurora and Chazy sites, respectively. At the Geneva site WAS, SH, AC, PMN, pH, P, K and Zn showed significant tillage effects. The cover crop effect was only significant for SH and PMN measurements. Indicators that gave consistent performance across locations included WAS, OM and AC, while PMN and RDP were site and management dependent. The composite soil health index (CSHI) significantly differentiated between contrasting management practices. The CSHI for the Willsboro site was 71% for NT and 59% for PT, while at the Aurora site it was 61% for NT and 48% for PT after 15 years of tillage treatment

Fusarium wilt incidence and common bean yield according to the preceding crop and the soil tillage system

The objective of this work was to evaluate the effects of preceding crops and tillage systems on the incidence of Fusarium wilt (Fusarium oxysporum f. sp. phaseoli) and common bean (Phaseolus vulgaris) yield. The cultivar BRS Valente was cultivated under center‑pivot irrigation in the winter seasons of 2003, 2004 and 2005, after several preceding crops established in the summer seasons. Preceding crops included the legumes Cajanus cajan (pigeon pea), Stylosanthes guianensis, and Crotalaria spectabilis; the grasses Pennisetum glaucum (millet), Sorghum bicolor (forage sorghum), Panicum maximum, and Urochloa brizantha; and a consortium of maize (Zea mays) and U. brizantha (Santa Fé system). Experiments followed a strip‑plot design, with four replicates. Fusarium wilt incidence was higher in the no‑tillage system. Higher disease incidences corresponded to lower bean yields in 2003 and 2004. Previous summer cropping with U. brizantha, U. brizantha + maize consortium, and millet showed the lowest disease incidence. Therefore, the choice of preceding crops must be taken into account for managing Fusarium wilt on irrigated common bean crops in the Brazilian Cerrado