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Over the last century, climate change, adoption of new regulations, and changes in cropping systems have significantly impacted weed and pest management in horticultural crops. The objective of this workshop was to provide a critical review of major changes and discuss current and future trends for weed and pest management. Speakers touched on a broad range of topics including climate change and disease dynamics, the use of disease resistance inducers, soil management for pest management, and the role of allelopathy in weed management. Major recommendations included 1) increased grower education related to the impact of climate change on plant diseases; 2) more research directed towards a better understanding of the interaction of plant–pathogen–inducer; 3) use of organic soil amendments, cover crops, crop rotations, and resistant cultivars to enhance the weed and disease suppressive effect of soils; and 4) enhancement of allelochemical production and subsequent weed suppression through conventional breeding and molecular techniques.

Weed management is critical in hazelnut (Corylus avellana) production. Weeds reduce nutrient availability, interfere with tree growth, and reduce hand-harvesting efficiency. Field experiments were conducted from Fall 2006 to 2010 to test effects of brassica (Brassica sp.) cover crops and hazelnut husk mulch as alternative weed management strategies in hazelnut. The cover crop treatments consisted of rape (Brassica napus), field mustard (Brassica rapa), oriental mustard (Brassica juncea), and fallow with no cover crop. Hazelnut husk was surface-applied at two thicknesses, 5- and 10-cm-thick layer. Dry biomass production by the cover crops was relatively consistent among years with oriental mustard producing the most biomass. Throughout the growing seasons, the cover crops reduced weed density, weed dry weight, and the number of weed species when compared with the fallow treatment. The most effective cover crop at suppressing weeds was oriental mustard. Hazelnut husk applied as a 10-cm-thick layer on the ground was highly effective at controlling weeds up to 180 days after application and reduced total weed dry weight by 83% at the end of the season. Our findings indicate that brassica cover crops or hazelnut husk may help control annual weed species in hazelnut orchards during early summer. However, these strategies should be combined with other methods like chemicals or cultivation for adequate weed management.

Field and laboratory bioassay studies were conducted to determine the impact of Brassicaceae cover crops on cucurbit germination percentages and stand counts. A 2-year field study in southwestern Michigan examined the effect of oilseed radish (Raphanus sativus var. oleiferus), oriental mustard (Brassica juncea), and yellow mustard (Sinapis alba) green manures on muskmelon (Cucumis melo Group reticulatus) stand. All three cover crops reduced direct-seeded muskmelon stand count as well as transplant survival. Stand count for direct- seeded muskmelon was greater than 85% for control and methyl bromide treatments and less than 41% for cover crop treatments. Oilseed radish had the greatest effect with 0% muskmelon stand in both years. The use of transplants improved muskmelon stand establishment. However, stand count (less than 45% to 50%) was still unacceptable. In bioassays, muskmelon, cucumber (Cucumis sativus), and honeydew melon (Cucumis melo Group inodorus) seeds were exposed to either non-lyophilized or lyophilized root and shoot aqueous extracts of oilseed radish. Germination percentages and radicle elongation measurements showed both extracts impacted all three crops to varying degrees. Muskmelon germination was least sensitive to the extracts, followed by cucumber, then honeydew. Cucumber and muskmelon root growth was equally inhibited by non-lyophilized shoot extract, while honeydew growth was mildly stimulated at 5% and 12.5% concentrations. Overall, non-lyophilized root extract showed stronger inhibition on seed germination than non-lyophilized shoot extract, while the reverse was true of lyophilized extracts. In general, non-lyophilized extracts had far greater impact on germination percentages and radicle elongation than lyophilized extracts. These results suggest species and tissue dependent toxicity of the cover crops as well as differential susceptibility of the cucurbit crops tested. Therefore, a plant-back period longer than the 8 days used in this study should be observed after cover crop incorporation before cucurbit seeding or transplanting.

Organic agriculture is growing in importance worldwide. In the United States, the rate of increase of organic growers was estimated at 12% in 2000. However, many producers are reluctant to undertake the organic transition because of uncertainty of how organic production will affect weed population dynamics and management. The organic transition has a profound impact on the agroecosystem. Changes in soil physical and chemical properties during the transition often impact indirectly insect, disease, and weed dynamics. Greater weed species richness is usually found in organic farms but total weed density and biomass are often smaller under the organic system compared with the conventional system. The improved weed suppression of organic agriculture is probably the result of combined effects of several factors including weed seed predation by soil microorganisms, seedling predation by phytophagus insects, and the physical and allelopathic effects of cover crops.

Field studies were conducted in 2003 and 2004 to determine effects of withholding irrigation on pepper (Capsicum annuum) plant height, leaf chlorophyll content, yield, and irrigation water use efficiency. Irrigation treatments were initiated at pepper transplanting (S0), after transplant establishment (S1), at first flower (S2), at first fruit (S3), or at fruit ripening (S4). The control treatment received only enough water to apply fertigation (FT). Withholding irrigation did not affect pepper plant height except FT treatment, but increased leaf chlorophyll content. Withholding irrigation until S4 saved 50% and 41% of irrigation water in 2003 and 2004, respectively, without affecting fruit yield compared with the treatment where irrigation started at transplanting. However, yield in the FT treatment was significantly reduced. Irrigation water use efficiency (pepper yield per unit area per millimeter of water applied) was maximum at S4 (59.1 kg·ha⁻¹ per millimeter) and S3 (24.1 kg·ha⁻¹ per millimeter) in 2003 and 2004, respectively. Similar trends in response of pepper to the irrigation treatments were observed in 2003 and 2004 even though there were large differences in rainfall, and pepper yield between years. This suggests that withholding irrigation until first fruit may help to maintain pepper yield while reducing irrigation costs. However, it is important to have adequate soil moisture at transplanting to insure adequate transplant establishment.

The effects of cover crops on nutrient cycling, weed suppression, and onion (Allium cepa) yield were evaluated under a muck soil with high organic matter in Michigan. Four brassica cover crops, including brown mustard (Brassica juncea ‘Common brown’), oilseed radish (Raphanus sativus ‘Daikon’), oriental mustard (B. juncea ‘Forge’), and yellow mustard (Sinapis alba ‘Tilney’), as well as sorghum sudangrass (Sorghum bicolor × S. sudanense ‘Honey Sweet’) produced similar amount of biomass and recycled similar amounts of nitrogen, phosphorus, and potassium. The brassica cover crop biomass contained more calcium, sulfur, and boron, but less magnesium, iron, manganese, copper, and zinc than sorghum sudangrass. However, soil fertility was generally similar regardless of whether a cover crop was used. This was mainly because the soil was sampled when most of the cover crop residue was not yet decomposed. Weed density during onion growth was reduced by all cover crops compared with the control with no cover crop, with yellow mustard treatment having the lowest weed density among the cover crops. Weed species composition was also significantly affected by the cover crops. Yellow mustard treatment had the lowest density of common purslane (Portulaca oleracea) and redroot pigweed (Amaranthus retroflexus), whereas sorghum sudangrass had the highest yellow nutsedge (Cyperus esculentus) density among all the treatments. However, weed suppression was not enough to eliminate normal control strategies. The brassica cover crops, especially oilseed radish and yellow mustard, increased onion stand count and marketable yield. These results suggest that brassica and sorghum sudangrass cover crops could provide multiple benefits if incorporated into short-term onion rotations under Michigan growing conditions.

How do you teach community supported agriculture (CSA) principles, small-scale organic farming, and local food issues at a major land grant university and develop related small-scale farming research and outreach? You create a place and opportunities for students, staff, and faculty to work together with the soil and plants to raise food in a non-classroom farm setting. After several years of discussion and obtaining funding, the Michigan State University (MSU) Student Organic Farm (SOF) CSA started in May 2003 with 25 memberships and increased to 50 after 1 year. The farm allows experiential learning of CSA management, crop selection, scheduling, maintenance, harvest, and organic farming methods. The CSA helps many MSU students and faculty see the value of supporting local organic food systems. With more than 3 years of experience working with students to run the SOF and the CSA, we are in the process of developing an organic farming certificate program. A total of 40 credits will include 12 months on campus plus a 16-week on-farm internship. The program has three major components: 1) organic farming courses with seven one-credit courses; 2) horticultural crop production courses with eight courses for a total of 15 credits; and 3) approximately 20 credits of experiential course work combined with classroom and independent learning.

Removal and disposal of polyethylene mulch in vegetable production represents a high economic and environmental cost to society. This study was conducted in 2006 and 2007 at Michigan State University to test the field performance of new biodegradable mulches using ‘Mountain Fresh Plus’ tomato (Solanum lycopersicum) as a model crop. Treatments included two biodegradable mulches (black and white), each with two thicknesses (35 and 25 μm). A conventional low-density polyethylene (LDPE) mulch of 25 μm was included as a control (a mulch commonly used by vegetable growers). Data loggers were installed 2 cm into the soil under the various mulches to record soil temperature. The experiment used a randomized complete block design with four replications. The mulches were used on a raised bed, drip irrigation system. Mulch degradation, soil temperature, tomato growth, weed density, and biomass were assessed during the seasons. Tomatoes were harvested at maturity and were fruit graded according to market specifications. Results indicate that soil temperature under the biodegradable mulches was greater than that under the LPDE mulch during the first week. Starting the second week, soil temperature dropped gradually under all the biodegradable mulches. The drop in temperature was greatest with the white mulch. Due to premature breakdown of the white mulches, weed pressure was high, resulting in smaller plants with low yield in 2007. Tomato growth, yield, and fruit quality from the black mulch was equivalent to that in the LDPE mulch. Future studies will optimize biodegradability of the mulches and test mechanical laying of the black mulch under commercial production.

Unfavorable environmental conditions, pests, and viral diseases are among the major factors that contribute to poor growth and quality of tomato (Solanum lycopersicum) seedlings in tropical areas. Improving crop microclimate and excluding insects that transmit viruses may improve transplant quality and yield in production fields. This study was carried out in two seasons at the Horticulture Research and Teaching Field of Egerton University in Njoro, Kenya, to investigate the effects of agricultural nets herein called eco-friendly nets (EFNs) on germination and performance of tomato seedlings. Tomato seeds were either raised in the open or under a permanent fine mesh net (0.4-mm pore diameter). Eco-friendly net covers modified the microclimate resulting in significantly higher day temperatures and relative humidity, compared with the open treatment. Nets increased temperature and relative humidity by 14.8% and 10.4%, respectively. Starting seeds under a net advanced seedling emergence by 2 days and resulted in higher emergence percentage, thicker stem diameter, more leaves, and faster growth leading to early maturity of seedlings and readiness for transplanting. Netting improved root development by increasing root quantity and length. Stomatal conductance (g _S) and estimates of chlorophyll content were higher in seedlings under net covering compared with those in the noncovered control treatment. Insect pests and diseases were also reduced under net covering. The use of the net in the production of tomato transplants presented a 36.5% reduction in the cost of seeds, through improved emergence and reduced pest damage. All other factors held constant, healthy and quality transplants obtained under a net covering also translate into better field performance; hence, increasing economic returns for commercial transplants growers, as well as for tomato farmers. Results of this study suggest that EFNs can be customized not only for their effective improvement on growth and quality of tomato transplants but also for their pest and disease management in the nursery alone or as a component of integrated pest and disease management.