Robert L. Bugg

Using cover crops to manage arthropod pests of orchards: A review

Abstract A review of entomological studies of cover crops for tree nuts, pome fruits, stone fruits, and citrus suggests both opportunities and challenges. Various cover crops harbor distinctive complexes of beneficial and pest arthropods, and diverse trophic relationships have been well documented in the literature. More study is required to determine: (1) whether cover cropping modifies orchard microclimate and target crop nutritional status and thereby influences pest dynamics; (2) whether and how cover crop species composition, spatial interspersion of species, and management by irrigation, mowing, and tillage affect build-up and movement of arthropods, and resultant pest damage to the target crop.

Ichneumonidae (Hymenoptera) Using Extrafloral Nectar of Faba Bean (Vicia Faba L., Fabaceae) in Massachusetts

ABSTRACT Sixty specimens of Ichneumonidae (Hymenoptera), representing 20 species and 4 subfamilies, fed at the extrafloral nectaries of faba bean (Vicia faba L., cv ‘Ipro’, Fabaceae) grown in replicated plots. Of those attacking lepidopterous pests, 3 species were known parasites of agricultural pests, 2 of forest insects, and 3 of both agricultural and forest pests. Eleven species had no recorded hosts. Faba bean seeded July 31st attracted large numbers of Ichneumonidae from mid-September through mid-November, may have provided food for overwintering adults of several of the species involved. Testing should continue on faba bean grown in conjunction with orchard, vegetable, and forest crops, because it can enhance soil fertility, and may help to sustain parasites of lepidopterous pests.

Insects associated with cover crops in Massachusetts.

ABSTRACTInsect faunae were evaluated for ten cover crops grown in two replicated trials. Five crops were assessed in the principal experiment: (1)Faba bean, Vicia faba L. cv ‘Ipro’ (Fabaceae); (2) Hairy vetch, Vicia villosa Roth (Poaceae), planted in mixture with rye, Secale cereale L. cv ‘Aroostook’ (Poaceae); (3) Annual white sweetclover, Melilotus alba Desrousseaux var. annua Coe cv ‘Hubam’ (Fabaceae); (4) Grain sorghum, Sorghum bicolor (L.) Moench cv RS-610 (TE-66) (Poaceae); and (5) Buckwheat, Fagopyrum esculentum Moench (Polygonaceae). An ancillary experiment concerned an additional 5 crops: (1)‘Austrian Winter’ field pea, Pisum sativum L. var arvense(L.) Poiret (Fabaceae) interseeded with rye; (2) Canadian field pea, P. sativum var. arvense, interseeded with rye; (3)Cowpea, Vigna unguiculata(L.) Walpers ssp. unguiculata cv ‘Mississippi Silver’ (Fabaceae); (4)Maximilian sunflower, Helianthus maximiliani Schrader cv ‘Aztec’ (Asteraceae); and (5)Canola, Brassica napus L. (Brassicaceae).Shake samples a...

Understory cover crops in pecan orchards: Possible management systems

Annual legumes and mixtures of annual legumes and grasses can perform several functions as understory cover crops in pecan orchards, such as providing nitrogenrich organic matter to improve soil fertility, or by sustaining lady beetles and other arthropods that may aid the biological control of pecan pests. Remaining questions concern selection of appropriate plant materials; whether to use cover crops singly or in mixtures; how to ensure reseeding as well as a substantial N contribution; whether, when, and how to use mowing and tillage; and fertilization options. Different considerations apply when dealing with cool- vs. warm-season cover crops. With minor adjustments, growers could adapt present cultural practices to include cool-season cover crops. These could be used throughout the orchard, by establishing appropriate self-reseeding species and avoiding both excessive mowing and indiscriminate placement of N-rich fertilizers. Within alleys, alternating 2-m strips of cool-season cover crops could be tilled in mid to late April or allowed to mature. The tilled strips would supply N to pecan trees immediately, whereas the adjoining untilled (remnant) strips could be mowed after seed is mature, to ensure dispersal of seed and reestablishment of cover crops over the entire alley. Cool-season annual legumes that die or are killed in late spring will probably furnish N and other nutrients at a suitable time, particularly in orchards with sprinkler irrigation. Warm-season cover crops, if desired, should be restricted to alleys to reduce possible competition with pecan. Alleys provide better illumination than do tree rows during periods when pecan trees are in leaf, and the tillage mentioned above will encourage emergence of warm-season cover crops. If these die or are killed in late summer or early fall, timing of N release may not be optimal, in the absence of adequate irrigation. Many options and tradeoffs need to be explored before choosing a cover-crop system. Attimes, several objectives may appear to conflict, and even delicately-managed mixtures of species may not fulfill all the desired functions.

Predatory and Parasitic Wasps (Hymenoptera) Feeding at Flowers of Sweet Fennel (Foeniculum vulgare Miller var. dulce Battandier & Trabut, Apiaceae) and Spearmint (Mentha spicata L., Lamiaceae) in Massachusetts

ABSTRACT Sweet fennel (Foeniculum vulgare Miller var. dulce Battandier & Trabut, Apiaceae) and spearmint (Mentha spicata L., Lamiaceae) grew and flowered in 0.5 × 1.0-m plots located amid an organic market garden (Site 1). During 1985, twelve, approximately-weekly sets of aerial-net collections were made from August 7th through October 22nd from single experimental plots planted to each of the two species. On each date, samples were taken during three-minute episodes at hourly intervals from 0830–1630 EDST. Additional nearby plantings of sweet fennel in an herb garden (Site 2) were used for occasional supplemental sampling of flower visitors. Sweet fennel flowered throughout the 12 weeks of sampling. Four hundred and ninety-seven insect specimens were collected from the small plot of sweet fennel occurring in Site 1, with 195 representing taxa that are at least in part predatory and 105 representing groups that are at least partially parasitic. Hymenoptera collected from sweet fennel at Sites 1 and 2 incl...

Comparison of 32 Cover Crops in an Organic Vineyard on the North Coast of California

ABSTRACT In a replicated study conducted from 1990 to 1992, cover crops and a control (resident vegetation) were evaluated in an organic wine-grape vineyard (cv. ‘Chardonnay’), located at a valley floor site in Hopland, Mendocino County, California. The purpose was to assess plant phenology, stature, biomass production, competitiveness with resident vegetation, and second-year stand regeneration or persistence in an unfilled vineyard. Legumes (Fabaceae) evaluated included nine annual and two perennial types of clover (Trifolium spp.), bell bean and three other types of Vicia, two types of coolseason annual medic (Medicago spp.), field pea (Pisum sativum ssp. arvense), a mixture of biennial sweetclovers (Melilotus alba and M. officinalis), broadleaf birdsfoot trefoil (Lotus comiculatus). There were six types of cool-season annual grasses (Poaceae) including three cereal grains. Native Californian perennial grasses included one rhizomatous and five bunch types. The sole representative of Brassicaceae was bl...

Soilborne pathogens in a vegetable double-crop with conservation tillage following winter cover crops

Abstract A cucumber-cucumber double-crop followed by a cucumber-snap bean double-crop was grown in a system using conservation tillage in relay-cropping following winter cover crops. Twenty different winter covers were legumes, grasses, legume-grass mixtures, crucifers, or fallow (no cover, resident vegetation). Population densities of Pythium spp. (primarily P. irregulare ) and Rhizoctonia solani anastomosis group (AG-4) were greater following legumes than following grasses or fallow; legume-grass mixtures and crucifers were intermediate. Cucumber fruit rot (induced primarily by R. solani AG-4) was more severe following legumes and crucifers than following grasses; legume-grass mixtures were intermediate. In the snap bean crop following cucumber, root and hypocotyl diseases were more severe following winter covers of legumes or fallow than following grass or legume-grass mixtures; crucifers were intermediate. Root-knot nematodes ( Meloidogyne incognita ) caused injury to the second vegetable crop each year in all winter cover rotations.

Tarnished plant bug (Hemiptera: Miridae) on selected cool-season leguminous cover crops.

Replicated field trials indicated that tarnished plant bug (TPB), Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae) attained relatively-high densities on hybrid vetches, Vicia sativa L. X V. cordata Wulf cv ‘Cahaba White’ and ‘Vantage’, lower densities on crimson clover, Trifolium incarnatum L. cv ‘Dixie,’ and particularly-low densities on subterranean clover, Trifolium subterraneum L. cv ‘Mt. Barker’. Densities of TPB were also relatively low on an additional 10 types of subterranean clover, including 7 cultivars representing T. subterraneum, 1 cultivar of T. brachycalycinum Katznelson and Morley, and 3 of T. yanninicum Katznelson and Morley. Field longevity trials indicated that late-instar and adult TPB lived longer when caged on crimson clover than on hybrid vetch, which in turn supported better survival than did subterranean clover. When adult TPB were caged on hybrid vetch or subterranean clover with or without floral and fruiting structures, there was no evidence that the presence of thes...

Foliar-applied seaweed and fish powder do not improve yield and fruit quality of organically grown processing tomatoes

ABSTRACT In a replicated field plot study conducted during 1994 and 1995 in the Sacramento Valley, California, U.S.A., combinations of three levels each of soil-applied organic fertilizing materials and foliar-applied seaweed and fish powder were tested on processing tomato (Lycopersicon esculentum Mill.), cv. Orsettis Halley 3155 to determine effects on crop yield, fruit quality and economics. The experimental design was a factorial split plot arranged in a randomized complete block with four replicates. Main plot treatments consisted of three soil fertility levels: (1) control, (2) woolypod vetch (Vicia villosa Roth ssp. varia [Host] Corbiere), cv. Lana and (3) Lana vetch and poultry manure compost. Subplot treatments consisted of three foliar spray levels: (1) control, (2) seaweed and fish powder applied at label rate, and (3) seaweed and fish powder applied at twice the label rate. The study was designed to simulate practices used by growers of organic processing tomatoes in the area. No significant differences were found for yield or quality of marketable fruit in any soil and foliar treatment combination in either year. Because no significant differences for yield or fruit quality were detected, no economic benefit for seaweed and fish powder can be inferred under the experimental conditions.