R. H. Walser

Control of iron chlorosis in apple trees with injections of ferrous sulfate and ferric citrate and with soil‐applied iron‐sul

Abstract Chlorotic ‘Red Delicious’ apple (Malus domestica Borkh) trees located in Utah County, Utah, were treated for iron deficiency through pressure injection and soil treatment in September, 1981. Injection treatments were either ferrous sulfate (FeSO4 · 7H2O) or ferric citrate (FeC6H5O7 · H2O) at rates of 100 ml of 1% solution per year of tree age. The soil treatment was surface‐broadcast acidified iron‐rich mining residue (iron‐sul) at approximately 1 kg per year of tree age. Chlorotic conditions were completely eliminated by the spring of 1982 by ferrous sulfate injection. Ferric citrate injection decreased, but did not completely eliminate iron chlorosis. Visual observations were similar in 1983. The iron‐sul treatment gave no apparent improvement of the chlorotic condition in the first season after treatment, and only slight improvement the second year. The improvement in chlorotic conditions gave correspondingly heavier fruit set, higher chlorophyll levels and greater shoot growth for trees injec...

Increased Fe‐efficiency in soybeans through plant breeding related to increased response to Fe‐deficiency stress. I. Iron stress response

Abstract A7, a new soybean [Glvcine max (L.) Merr.], developed through plant breeding is considered to be more Fe‐efficient than cultivars currently available. The objective of this investigation was to determine if recognized factors in the Fe‐stress response mechanism may have been altered in A7 soybean to make it more Fe‐efficient than the A2, Hawkeye (HA) and Bragg (Fe‐efficlent) and the Pride B216 (Pride), T203, and Anoka cultivars (Fe‐inef‐ficient). The release of hydrogen ions and ‘reductants’ by the roots were the two parameters of the Fe‐stress response studied in this investigation. The effect of plant number per liter of solution was also considered by using 20 and 28 plants per 14 liters of nutrient solution. Compared to A2, HA, Bragg, Pride, Anoka and T203 soybean cultivars, A7 released more hydrogen ions and ‘reductant’ from its roots in the zero Fe treatment and also maintained higher Fe and chlorophyll concentrations. This could explain why A7 soybean grows better than the other soybeans o...

Iron‐stress response mechanism and iron uptake in iron‐efficient and ‐inefficient tomatoes and soybeans treated with cobalt

Abstract The influence of Co on Fe uptake and the Fe‐stress response mechanism of tomatoes (Lycopersicon esculentum Mill.) and soybeans [Glycine max (L.) Merr.] was studied. Iron‐efficient and ‐inefficient plants (T3238 fer + and T3238 fer tomatoes and A7 and T203 soybeans, respectively) were grown in nutrient solutions for seven and nine days at varying Fe and Co levels (0, 0; 1.0, 0; 1.0, 0.3; 1.0, 0.6; 1.0, 1.2; 1.0, 2.4; and 0, 1.2 mg liter–1 Fe and Co, respectively). Cobalt significantly (p≤0.05) decreased chlorophyll and foliar Fe and increased foliar and root Co in all cultivars. Cobalt effects on root Fe varied among cultivars. The Fe‐inefficient cultivars were most susceptible to chlorosis in the presence of Co, yet apparently exhibited true Fe deficiency. The Fe‐efficient cultivars appeared to exhibit a combination of Fe deficiency and Co toxicity. Chlorophyll formation was generally limited when foliar Fe was below 50 ug Fe g–1 dry weight regardless of Co treatment. Reductant and proton excreti...

Increased Fe‐efficienchy in sotbeans through plant breeding related to increased response to Fe‐deficiency stress. II. Mineral nutrition

Abstract Iron efficiency in A7 soybean [Glycine max (L.) Merr.] was increased through plant breeding, and it was determined in a companion paper that A7 soybean responded to Fe‐deficiency stress by increased exudation of H and reductants at a lower Fe concentration than the Fe‐efficient Hawkeye (HA), A2, and Bragg, and the Fe‐inefficient Pride B216 (Pride), Anoka, and T203 soybean cultivars. The objective of this paper was to assess how soybean response to Fe‐deficiency stress affected the general nutrition of the plant. Response to Fe‐deficiency stress (H ion and reductant extrusion) was not a good index of total Fe taken up by the plant at higher levels of Fe. For example, as the Fe concentration in solution increased, Bragg took up much more Fe and Mn into both tops and roots than did the other cultivars tested. Pride behaved very much like Bragg and if grown where the supply of Mn is plentiful may develop Mn‐toxicity symptoms. With the addition of Fe, both Cu and Zn concentration decreased in tops and...

Organic and Conventional Peach Production and Economics

ABSTRACT A two year study was undertaken to compare organic peach (Prunus persica (L.) Batsch) production with conventional production. Peach trees treated with nitrogen containing fertilizers (dairy manure and NH4NO3) were more vigorous, productive, and cold hardy than trees treated with an organic seaweed product or the nontreated controls. Organic production inputs were more costly than conventional inputs, however, these greater costs were more than compensated for by high market prices which lead to higher net returns for organically produced peaches. A taste test found no significant preference for either organic or conventional peaches.

Response of dry beans to iron deficiency stress

Abstract Two dry bean (Phasaolua vulgarla L.) cultivars, one susceptible (PI‐165078 (PI)) and one resistant (Great Northern Valley (GNV)) to Fe deficiency chlorosis in the field were grown in a modified Hoagland solution in a growth chamber under varying degrees of Fe stress (0.0, 0.05, 0.10, and 1.0 mg Fe/liter). Response to Fe‐deficiency stress was determined by measuring daily release of H ions and reductant from the roots, leaf chlorophyll and concentrations of Fe and Mn in leaves and roots. As the plants responded to Fe stress, both varieties released H ions and reductant from their roots, with GNV responding sooner than PI. There were generally no significant differences between cultivars in chlorophyll concentration. The Fe concentration in top leaves was not significantly different between cultivars at solution Fe levels below 1 mg/liter. There was some indication that GNV might be more Fe‐efficient at the 0.05 mg Fe/liter treatment than PI, but these two dry bean cultivars are similar enough in t...

Efficacy and Economics of Codling Moth Control in Organic and Conventional Pome Fruit Production

ABSTRACT Use of rotenone and pyrethrum to organically control codling moth (Laspeyresiapomonella (L.)) at different population densities was examined for efficacy and economics. Conventional treatments of azinphosmethyl gave the best control at all population densities. Only when codling moth populations were low could rotenone or pyrethrum provide adequate control. The highest degree of organic control was achieved with a mixture of rotenone and pyrethrum. Economic assessments indicated that the higher costs of organic production could be offset by direct grower retailing to consumers of organic produce. These results suggest that economical organic codling moth control can be achieved in orchards of low and medium codling moth density provided growers take full advantage of premium price opportunities in the organic market.