There is interest in identifying cultural practices that may reduce fungicide requirements of creeping bentgrass (Agrostis palustris Huds.) putting greens. Our objective was to evaluate the plant defense activator ASM in combination with 12 biostimulants for the potential to reduce dollar spot (Sclerotinia homoeocarpa F.T. Bennett) and brown patch (Rhizoctonia solani Kuhn) in a blend of `Cato: `Crenshaw creeping bentgrass during 2000 and 2001. The experimental design was a split-plot with ASM as the whole plot, and biostimulants as the subplots. ASM was applied biweekly as a.i. at 35 g·ha-1 and biostimulants were applied according to manufacturers recommendations. Sclerotinia homoeocarpa infection centers were reduced by 38% with ASM, but levels were >1500/m2 in Aug. 2000, and turf quality was unacceptable through most of the study period. No suppression of brown patch occurred with ASM. None of the biostimulants reduced dollar spot or brown patch in creeping bentgrass when compared to biweekly applications of soluble N at 4.9 kg·ha-1. Dollar spot suppression achieved with ASM warrants additional studies to determine how it might be used to reduce fungicide inputs on creeping bentgrass putting greens. Chemical name used: acibenzolar-S-methyl (ASM).
Joon Lee, Jack Fry, and Ned Tisserat
Hanan M. El-Hoseiny, Mohamed N. Helaly, Nabil I. Elsheery, and Shamel M. Alam-Eldein
have been considered some of the major causes for alternate bearing in mango ( Chadha, 1993 ). Some field practices, such as foliar spray of organic biostimulants (e.g., humic acid, fulvic acid, and amino acids) and micronutrients (e.g., Fe, Zn, Mn, Cu
Marc van Iersel
Various growth stimulators have been reported to improve plant growth. Some of these are formulated to improve root growth, which would be particularly beneficial for reestablishing transplants. Three commercially available plant growth stimulators—PGR IV (MicroFlo, Lakeland, Fla.), Roots2 (Lisa Products Corp., Independence, Mo.), and Up-Start (The Solaris Group, San Ramon, Calif.)—were tested to quantify their effect on post-transplant growth of petunia (Petunia × hybrida Hort. Vilm.-Andr.) and impatiens (Impatiens wallerana Hook.f.) seedlings and to assess their value for the greenhouse industry. Seedlings were transplanted from plug flats into larger 5.6-fl oz (166-cm3) containers and treated with 1.1 fl oz (31 mL) of growth stimulator per plant (22 fl oz/ft2). Applications were made immediately after transplant. None of the treatments affected root mass at any time. Up-Start (2 fl oz/gal) increased final shoot dry mass by ≈20% compared to the control plants. The increase in shoot growth by Up-Start most likely is caused by the fertilizer it contains. Up-Start also increased flowering of petunia from 34 to 40 days after transplant. PGR IV (0.5 fl oz/gal) and Roots2 (1.28 fl oz/gal) did not affect dry mass of the plants. PGR IV increased the number of flowers of petunia and impatiens, but this effect occurred well after the plants were marketable. Roots2 caused a small delay in early flowering and an increase in late flowering of petunia but had no effect on flowering of impatiens. Since the effects of the growth stimulators was either due their fertilizer content (Up-Start) or occurred after the plants would have been sold (PGR IV, Roots2), none of the growth stimulators appears to be beneficial for bedding plant producers.
Brian P. Gibbons, Timothy J. Smalley, and Allan M. Armitage
Three biostmulants, Grow-plex (Menefee Mining Corp., Dallas, Texas), Roots 2 (LISA Product Corp., Independence, Mo.), and Root n' Shoot (Natural Organic Products International, Mount Dora, Fla.) were applied to transplanted plugs of Salvia splendens `Empire Red' and Begonia semperflorens-cultorum `Varsity Pink' and `Varsity Brite Scarlet'. Root n' Shoot drench (0.78%) solutions at transplant increased root weight, but a 1.56% solution decreased root weight of salvia; however, shoot growth was unaffected. Root n' Shoot decreased shoot growth of begonia, but did not affect root growth of begonia. Roots 2 treatments (0.25% or 2.00%) increased shoot weight of salvia, but did not affect salvia root growth or root or shoot growth of begonia. Spraying Grow-plex (0.78% or 1.56%) to runoff at transplanting and 2 weeks after transplanting did not affect root or shoot growth of salvia or begonia.
M.L. Elliott and M. Prevatte
Three bone products (meat and bone meal, steamed bone meal, and bone chips) were compared to a water-soluble P source (monocalcium phosphate) for P availability and enhancement of tomato shoot growth. All bone products were finely ground to pass through a 40-mesh sieve. The products were added to a phosphorus-deficient greenhouse growing medium based on their P concentration with P at 50, 100, 200, and 400 mg·kg−1. Meat and bone meal produced the least shoot growth in 1992, but all products were similar in 1993. Growth peaked with P at 111 mg·kg−1 in 1992, but in 1993, P at 50 mg·kg−1 was sufficient. Shoot P uptake was in direct proportion to P availability in the soil mix, monocalcium phosphate having the highest shoot P content. Although bone products affected N, Ca, Zn, and Mn content in shoots, the magnitudes of differences were minor and inconsistent from 1992 to 1993. Major consideration for using a bone product are its relative cost of P, fineness of grind, and CaCO3 equivalent.
J. Pablo Morales-Payan and William M. Stall
Experiments were conducted to determine the effects of a Siberian fir (Abies sibirica) extract rich in triterpenic acid (TTA), a seaweed (Ascophyllum nodosum) extract with cytokinin-like activity (CSE), and a mixture of amino acids and short-chain peptides from fermented animal tissue (APC) on broadleaf cilantro (Eryngiumfoetidum) shoot weight and leaf area. Aqueous solutions of CSE, TTA, and APC at various rates were applied individually on the broadleaf cilantro leaves 15 and 30 days after transplanting. Broadleaf cilantro leaf area and shoot fresh and dry weights were determined after harvest (60 days after transplanting). APC, TTA, and CSE significantly increased broadleaf cilantro shoot weights and leaf area as compared to control plants. Aqueous solutions of APC at the rate of 900 g·L-1, CSE at the rate of 50 mg·L-1, and TTA at the rate of 300 mg·L-1 resulted in the highest broadleaf cilantro shoot weights.
Giuseppe Colla, Mariateresa Cardarelli, Paolo Bonini, and Youssef Rouphael
impact of cropping systems ( Searchinger, 2013 ). One of the most promising technologies to tackle these rising challenges consist in the use of plant biostimulants which include natural substances, other than fertilizers and pesticides, able to promote
Chenping Xu and Beiquan Mou
nutritional quality of crops. The use of biostimulants to enhance crop growth and yield has gained considerable momentum for ecological sustainability and consumer health ( Calvo et al., 2014 ; du Jardin, 2015 ). Biostimulants are substances enhancing plant
Chenping Xu and Beiquan Mou
-Guerrero et al., 2008 ; Prapagdee et al., 2007 ; Xu et al., 2007 ). In addition, chitosan has become of interest as a crop biostimulant suitable for use in sustainable agriculture ( Pichyangkura and Chadchawan, 2015 ; Sharp, 2013 ). Extensive application of
Margaret T. Mmbaga, Lucas M. Mackasmiel, and Frank A. Mrema
and plant growth ( Figs. 1 , 4 , and 5 ). BCAs B17A and B17B appear to act as biostimulants and, as such, have the potential to contribute to the minimization of root rot and powdery mildew. The two bacterial BCAs were initially isolated from